• Choose a month

  • Rapt in Awe

    My Journey through the Astronomical Year

    Think of this as a "companion text" to this, the main web site. Not required reading, butI hope you'll find it interesting and helpful.

November 2011 Events: Feast in the East – and the West is no Slouch Either!

With the naked eye the planets look like stars and we can follow the path of the five brightest in our skies this month. With binoculars we can add Uranus and Neptune to our list and even see the four brightest moons of Jupiter. (NASA composite image. Click for larger version.)

It’s a feast in the east for November 2011 with Jupiter dominating that section of sky in the evening and Mars and Saturn taking over in the morning. Meanwhile, over in the west we have the Venus/Mercury show developing in the second week of the month.  And how about the middle of the sky? Well, there we have the always challenging-to-find planets, Uranus and Neptune.  Binoculars are a must to sight them. And if you’ve been counting, you know that’s all the planets! (Pluto – well, it’s a “dwarf planet” and it’s heading behind the Sun this month, and even if it were well placed it would be out of reach of the naked eye, binoculars, and even small telescopes.) Add to this a comet and the special fun the moons of Jupiter offer, and it really should be a very good month.

An appetizer: take a 2.5 million year star trek to the Great Andromeda Galaxy

But wait! That stuff is all in our back yard – we can get to any of those planets in a matter of minutes – light minutes, that is! (Light travels around the earth seven and a half times in a second , yet it takes it about 30 minutes to reach Jupiter!)  But early evenings in November – especially when there’s no moon to compete as will be the case in the last half of this November (2011) – offers another special treat for binocular users – the Great Andromeda Galaxy.

The Great Andromeda Galaxy as seen by the Hubble Space Telescope. It won't look quite like this, but you too can see it with binoculars.

This is our neighbor in space –a galaxy much like our own Milky Way. And with dark skies free of the worst of light pollution you can actually glimpse it with your naked eye if you know just where to look. And it really is a glorious sight in even ordinary binoculars, especially when you understand that the small cloud you see is really 300 billion suns and their light is reaching you after journeying for two and a half million years! I don’t mean to detract from the planetary show, but if you have binoculars and clear skies, you really should take this “trek.” It will be especially good during the last two weeks of the month when the Moon doesn’t wash it out.

Review the eastern sky chart in our “Look East” post for this month, then use the chart and instructions below to zoom in on this galaxy – and when you do, give yourself a pat on the back as a genuine star trekker.

To find the Andromeda Galaxy use half of the "W" of Cassiopeia as a pointer. Or take a star hop down Andromeda's Couch, then up a couple of hops as shown. You should be able to fit stars 3 and 4 in the same binocular field of view, then stars four and the galaxy in the same field. Click for a larger version. (Created from Stellarium screen shot.)

(Here’s a printer-friendly, black and white version of the chart above.)

Back to the planets – they  line up like this

  • Jupiter can’t be missed. It’s the brightest “star” low in the east right after sunset.
  • Venus gets started on one of its spectacular appearances during which it will dominate the western evening sky for months.
  • Mercury plays coy and hard to catch, but Venus gives it away as it peeks above the western horizon right after sunset.
  • Mars is getting higher and higher in the morning sky and actually rises before midnight for part of the month. It continues to scoot right along, this month playing tag with the bright, guidepost star, Regulus.
  • Saturn is a morning sky object that will excite telescope users because its rings are at last returning to a favorable tilt from our perspective.
  • Uranus and Neptune are the difficult ones. They are both reachable with binoculars and in prime time, but they are challenging to find.

So that’s the line-up – read on for details. Or jump ahead to what interests you by clicking on one of the links above.

The Feast in the East 1 – Jupiter and the Algol bonus

Jupiter is in its prime – and dominating our prime-time observing – nice and high, nice and big, and with dancing moons that you can even see in binoculars if you can only find a way to hold them steady enough. Fortunately, there are several neat techniques pictured here that you could use to hold any binocular steadier. I used the “rifle sling” technique pictured on that site with my 15X70s and it helped significantly. But no matter what the size of your binoculars, you increase your chances of seeing Jupiter’s moons if you can get them rock steady.

Most binoculars have a threaded center post that allows you to use an inexpensive adapter to mount them on a typical camera tripod. This is good as long as the object you are looking at is not too high in the sky. Once it gets above 45 degrees it’s very difficult to position yourself behind binoculars that are on an ordinary tripod. (Go here to see one example of tripod adapters for binoculars.) So this is a good approach this month up until about three hours after sunset as Jupiter climbs higher each hour.

When you are looking at Jupiter’s moons, it’s fun simply because they are constantly changing position from night to night – even from hour to hour. It’s also fun because they are surprisingly diverse worlds. In fact, the exploration of large moons throughout the solar system has been a constant source of surprise. So I suggest two things.

First, learn more about Jupiter’s moons by going here. (Pay special attention to the four “Galilean Moons” – those are the ones you see.)

Second, use this Javascript utility at Sky and Telescope to figure out which moon is which when you actually observe them..

And while we’re on the subject of handy tools at Sky and Telescope, also use their utility to figure out when it would be a good time to catch the surprisingly elusive Demon Star – aka Algol – when at its minimum. This is something you don’t need binoculars to see – it’s best done with the naked eye. I explained it in more detail last month.

Feast in the West – Venus and Mercury

Venus and Mercury line up almost due southwest with the sun setting halfway between southwest and west. BE SUPER CAUTIOUS! To see these you will need binoculars, but looking at the Sun with binoculars will cause immediate damage to your eyes. So wait 10-15 minutes after sunset, then start your search. Venus should be bright enough even in twilight to see with the naked eye once you know where to look, so it helps to find it first with binoculars. (Prepared form Starry Nights Pro screen shot.)

From roughly the 9th to 22nd of November 2011 Venus and Mercury will appear  in the same binocular field of view about 15 minutes after sunset. They are attractively aligned in an arc or line for just a few days starting on the 9th.  I’ve included Antares because it makes such a nice picture, but it’s more than a magnitude fainter than Mercury and much, much fainter than Venus (magnitude -3.8) and closer to the horizon, so I think it will be a difficult target. You need, of course, an unobstructed western horizon and very clear skies. Fifteen minutes after sunset Venus is less than a fist above the horizon. Half an hour after sunset it’s just half a fist high, and if you haven’t spotted it by then, you probably won’t as it will get lower fast and the closer to the horizon, the more difficult to see.

Please be careful and don’t begin your search with binoculars until 10 minutes after sunset so there’s no danger of catching the Sun in the binoculars and damaging your eyes. As the days go by Mercury stays about where you see it and Venus pulls away to the south, getting higher as Mercury begins to sink.

The Feast in the East 2 – Mars, Saturn, the Moon and stars

Now this is cool!  On November 22, 2011, you won’t have any trouble locating Saturn because it will be within a fist of the crescent Moon with Spica, about one magnitude brighter than Saturn, between it and the Moon. High above them,  Mars has passed Regulus, and is just about the same brightness as Saturn.  But you can find these planets just about any morning of the month, using the bright guidepost stars as your guide. Follow the arc of the Big Dipper’s handle and it takes you to Arcturus. Keep following this general curve and you get to Spica – passing through Saturn on the way.  Both Spica and Arcturus are  bright guidepost stars, as is Regulus. Mars will be within one fist (10 degrees) of Regulus all month. Mars starts out west (above) it on the first of the month, passes closest to it on the morning of November 11, and will be about one fist east (below) it by the end of the month.  Saturn will stay roughly half a fist (5 degrees) from Spica all month, changing position much more slowly than Mars since it is much farther away from us.

Click on image for a larger version. Prepared from Starry Nights Pro screen shot.

Challenge in the Middle – Uranus and Neptune

The early evening of the last half of the month is a good time to look for these planets since the Moon will not offer interference then – but you need to wait until about 90 minutes after sunset so it is completely dark.

This is where knowledge of the sky certainly helps – with a little knowledge it’s as easy as one, two – to find Uranus; and one, two, three to find Neptune. Here are the steps

One – Get your bearings.

Know the sky in the vicinity of these two planets. In particular you want to locate a relatively dim asterism known as the “Circlet” to guide you to Uranus, and two others, the “Water Jar” and “Arrowhead” to find Neptune. The starting point, however, is an asterism that should be familiar to you – the Great Square – and if it isn’t, please go to the “Look East” post for this month and locate it.  Then study the following chart – click on it to see the larger version.

Step one - get familiar with the big picture. The red circle between Uranus and Neptune is the field of view of typical, low-powered, binoculars - good tools for finding these objects. The Great Square and Jupiter should be easy to find because they're both bright. The "Circlet" is fourth and fifth magnitude stars that you need to be away from light pollution to find, but even in light pollution you can spot them with binoculars. However, the whole Circlet will probably not fit in your field of view. The Water Jar will fit in the typical binocular field and so may be an easier target. What I call the "Arrowhead" is the constellation Capricorn. The star at its northeastern corner is bright enough to see even in light-polluted skies and so is a good starting point for finding Neptune. Click image for larger version. Prepared from Starry Nights Pro screen shot.

Step 2 – Zoom in on Uranus . . .

Assuming you have located the Circlet, now turn to this chart. The brightness of the planet in comparison to nearby stars is a good guide and will give you some idea of what to look for and whether or not it’s visible in your skies. The numbers on the chart refer to the magnitude of a star or planet. They are given without a decimal point so as not to confuse the chart with dots that aren’t stars. Thus the number “51” means a magnitude of 5.1 – and remember, the lower the number, the brighter the star!

Scan below the Circlet with your binoculars. The little rectangle of fourth and fifth magnitude stars should be easy to pick up and will help you find Uranus. Note that Uranus at magnitude 5.8 is half a magnitude or so dimmer than the stars in the rectangle, but a bit brighter than the 6.3 star next to it. The position of Uranus will change very little during the month. Click on image for larger version.

  . . . or alternative Step 2, zoom in on  Neptune

Neptune is more challenging, but if you can locate the third magnitude star Deneb Algiedi in the northeastern corner of the Arrowhead asterism, you will be well on your way. (It’s on the bright side of third magnitude, so should be fairly easy to find.)

Once again, the numbers next to stars are their magnitudes with the decimal point left out. So Neptune is magnitude 7.9, for example. It will be right near the edge of visibility in low power binoculars and you'll need the next chart to pick it out from the background stars. Click image for larger version. Prepared from Starry Nights Pro screen shot.

And now Neptune Step 3 – up close and personal

The bigger – and steadier – your binoculars, the easier it will be to see Neptune. It’s also important that your eyes be dark adapted. You’ll be looking for a faint “star” among several. Here’s a close-up chart.

Click image for larger version. Prepared from Starry Nights Pro Screen shot.

Did I mention the comet?

The comet is one that requires binoculars, but it’s still fun and is unusual in that it will be with us right up to the spring. I’m talking about Comet Garradd which we met at the end of August and start of September when it was hanging around with my favorite binocular asterism, the Coathanger.  Here’s a chart for its path in the last half of November.

At 6th magnitude Comet Garradd is just below naked eye visibility for most of us, but you should be able to pick it up in binoculars as a faint, fuzzy star. I doubt very much that you'll see a tail, but if you do it should point the direction shown in the chart. The chart is for 90 minutes after sunset - look west and find the Keystone of Hercules as a starting point. The second and third magnitude stars - Rasalhague and Rasalgethc, should also be a big help in getting you in the right general area. Arrow shows movement of comet from November 15 to November 30 - a period when the Moon should not interfere with your search. On the 15th Comet Garradd will be about three fists above the horizon 90 minutes after sunset - by the end of the month it will be about two fists. Click image for larger version. Prepared from Starry Nights Pro screen shot.

And if you’re wondering where the November meteors went, the Moon ate them!

Yes, last year at this time we were talking about three minor – but interesting – meteor showers. They were the South and North Taurids and the Leonids.  They’ll still be around this year, but they are weak shares at best, and this year will be especially challenged by the Moon. But for the record, the South Taurids peak November 5/6 late night until dawn; the North Taurids November 11/12th; and the Leonids November 17/18.

Events: The planets in May 2011: Everyone’s at the party!

May offers a planet spectacular in three parts – first, the evening show where Saturn  meets the stunning double star, Porrima; then the full morning show where the rest of the the planets gather, and then the pre-dawn special, which Sky and Telescope magazine calls “the most compact visible gathering of four bright planets in decades.” Here’s a summary in pictures of each of these events with links at the end of each summary for more details and many more charts

Saturn Kisses Porrima

Here’s a simulation of Saturn’s dance with Porrima over the next two months, prepared with Starry Nights Pro software.

For the naked eye observer, watching Saturn and Porrima during May and June of 2011 provides a terrific opportunity to see a planet in retrograde motion – then pause,  then swing back in its normal eastward path against the background stars.  For the small telescope user it’s even better.  Porrima is a stunning double star when seen in a back-yard telescope – and Saturn, with its rings, the most awesome planet in a small telescope. During May and June of 2011 the pair come amazingly close – so close they’ll both fit in the same telescopic field of view near the end of May and in early June. For more details, go here.

The Full Morning Show

This shows you where six of the seven visible planets are in the eastern pre-dawn sky about 30 minutes before sunrise - however, to find Neptune and Uranus you'll have to look earlier when the sky is darker. And please - click this image for a larger view! (Prepared from Starry Nights Pro screen shot.)

Frankly, Neptune and Uranus will be easier to see later this year, but if you’re getting up early to see the pre-dawn gathering of four planets very close to one another, then why not get up a couple of hours earlier and do a search for the outer two planets, Uranus and Neptune? You’ll need binoculars, an unobstructed eastern horizon, and clear skies, of course. For more details, go here.

The Pre-dawn Special Show

Jupiter, Venus, Mercury, and Mars, as seen in the predawn sky of May 11 from mid-northern latitudes. I've modified this Starry Nights Pro screen shot to include images of the planets to scale - a reminder of what these faint morning "stars" actually look like up close and personal. Click image for a much larger version.

As mentioned, May’s pre-dawn skies brings us what Sky and Telescope calls “the most compact visible gathering of four bright planets in decades.” And it goes on most of the month! The best seats in the house for this show will be to the south – the farther south the better. Those of us in mid-northern latitudes will find it more challenging to see this  pre-dawn show, and for all an unobstructed eastern horizon and exceptionally clear weather is a must. If I’m hoping for one morning of exceptionally clear skies it would be for May 11 – but fortunately the show starts well before then and continues well after that date. Go here for more details and many more charts.

Saturn Kisses Porrima – the details!

The outer planets generally appear to move eastward against the backdrop of distant stars. However, as Earth overtakes a planet in its orbit and passes it, the planet appears to move backwards – westward – called retrograde motion.  Watch Saturn during May and June to see this change in reverse, for in this case during May Saturn is already in retrograde (westward) motion. Then in the first two weeks of June it appears to halt, stand still, then reverse itself to resume  eastward motion.  Though Saturn’s motion is very slow – it takes 29.5 of our years to complete a trip around the Sun – its motion is easy to mark this year as you note its changing relationship to the bright (magnitude 3.4) star Porrima.  This you can do with the naked eye, but the changes will be easier to see if you use binoculars and make a little chart.  At the start of May Saturn is about 1.5° from Porrima. By the end of the month it’s separated  from Porrima by less than 20 minutes of arc – about one third of a degree. During the first few days in June it will appear to stand still, then will slowly resume its eastward motion, putting more and more distance between it and Porrima. To observe all this, start with this chart, use your binoculars, and note its changing position. (You don’t have to start on May 1 – any day this month will do – but it will be good if you can check every week or so and draw in the changing position of Saturn. )

Here are Saturn and Porrima at the start of the month. Saturn is the brightest "star" at magnitude 0.54 and Porrima the next brightest at Magnitude 3.4. There are a couple of other stars in the field that are magnitude 6 and the rest should be visible in binoculars if you look carefully. Note: Porrima is always to the west of Saturn - but early in the evening it will feel more like it is "above" Saturn. Remember - west is the direction everything appears to move as the night goes on. Click image for a larger version. (Prepared from Starry Night Pro screen shot.)

To keep track of Saturn’s changing position night-to-night and see it  switch directions,  download this “printer friendly” version of the above chart.

For observers with telescopes this should make a stunning sight – especially during the first week of June. The trick will be to use an eyepiece that gives you enough magnification to split the very close pair of stars that is Porrima, yet include Saturn in the same field of view.  I’m planning to use a 4-inch refractor and a wide-field eyepiece delivering at least 150X. I’m honestly not sure if that will be enough – depends on conditions.  On April 29 I could fit the pair comfortably in a low power (22.5X) field. I could not get a clean split of Porrima at any power because the air was too turbulent. In theory I should be able to see both Saturn and a clean split of Porrima near the end of the month or in early June, but the weather will have to cooperate!  Not being sure if it will work is all part of the fun. You can read all about Porrima and how to split it in my friend John Nanson’s post on the star-splitting blog we share. Check it out here!

Incredibly, Porrima was apparently named for two sisters who were goddesses of prophesy. Since the name was given before they could possibly tell that Porrima was two stars, that’s sure some prophesy! If that’s the case, I’m sure we can assume Saturn – the Roman god of agriculture – is playing the shy farm boy,  giving them both a kiss,  then running. 😉

The Full Morning Show – in detail!

Finding Uranus and Neptune requires an early start in May, but with patience, both can be located using binoculars, though Neptune is a challenge because of its dimness and  Uranus because it’s still close to the horizon when it is dark enough to see. Let’s start with Uranus.

Finding Uranus - First see if you can locate the Circlet of Pisces about one fist above the eastern horizon and consisting of 4th and 5th magnitude stars. Binoculars will probably be needed for this. Click chart for larger view. Prepared from Starry Nights Pro screen shot.

Step 1 – The challenge in finding Uranus is you need a dark sky – but the planet is just getting high enough to view as astronomical twilight – the first hint of dawn – begins. So you might start looking for the circlet of Pisces about two hours before sunrise and after you locate it, look closer to the horizon for Uranus.  The Circlet consists of five stars that are about as bright as the four fainter stars in the Little Dipper. There are two others included in our chart and these are even fainter. The whole asterism may be just a little too large to fit in your binoculars. Here’s a printer friendly version of this first chart.

Step 2: The circle covers five degrees - about what you see in binoculars. Notice the distinctive trapezoid asterism to the left? That should serve as a good guide. Uranus will be just slightly brighter than the stars of this trapezoid. Click image for larger view. (Prepared from Starry Nights Pro screen shot.)

Step 2 – Between the Circlet of Pisces and the eastern horizon you should find Uranus about an hour before sunrise – but start looking a bit earlier. The sky will be getting brighter making it difficult to spot this magnitude 6 planet, even with binoculars.  Here’s a printer-friendly version of the above chart.

Finding Neptune

Finding Neptune is easier because it’s higher than Uranus while the sky is still fully dark. But at magnitude 7.9 it is significantly fainter and as far as I’m concerned it’s in a celestial wilderness where the constellations are not much help and there is little in the way of bright asterisms to point the way. But for those who enjoy a challenge, here are a couple of charts. The first is a broad overview and gives you an idea of the general territory. For me the most recognizable feature is the Great Square of Pegasus, but that’s pretty far away. Closer – but fainter – will be the Circlet of Pisces included on the Uranus chart.

This chart will just give you an idea of the general region in which to search for Neptune on May mornings about two hours before sunrise. Click image for much larger - and readable - version. (Prepared from a Starry Nights Pro screen shot.)

This is Neptune at mid-month. It is moving from right to left, but very slowly, so the chart is good for the month, just understand the position may not be exactly what you see here. Click image for larger version. (Prepared from Starry Nights Pro screen shot.)

Download a printer-friendly version of this chart.

Guide to the early morning planet show – in detail!

OK, it’s worth repeating – Sky and Telescope magazine calls this “the most compact visible gathering of four bright planets in decades.”  The farther south you go, the easier this show will be to see, but the general rules apply to all locations.

Where you are and when you look is important!

The further south you are the higher the planets will be at any given instant and the higher they are the earlier you can look. The earlier you look, the darker the sky background, making the planets easier to find.

Binoculars are a critical aid.

Nothing special is needed – any binoculars will help – but when trying to see the fainter of these planets – Mercury and Mars – binoculars are absolutely critical in northern latitudes and will help no matter where you are. DO STOP USING THEM 15 MINUTES BEFORE SUNRISE, HOWEVER. YOU DON’T WANT TO CHANCE LOOKING AT THE SUN WITH YOUR BINOCULARS. THAT IS DANGEROUS.  And if you haven’t seen the planets by 15 minutes before sunrise, you’re not going to see them – so just sit back and enjoy the dawn!

An unobstructed eastern horizon and clear skies are essential.

Your fist held at arm’s length covers about 10 degrees. In mid-northern latitudes the planets will not get above 10 degrees before it gets too light to see them.

Start looking early.

The charts that follow are for a time that strikes a balance between the altitude of the planets and the darkness of the background sky. But if a chart is for 30 minutes before sunrise, start looking at least 15 minutes prior to that – perhaps half an hour earlier. The planets will be lower then, of course, but in events such as these you are playing a game with the elements – the higher the planet, the easier to see – but as the planets gets higher, the sky background gets lighter and the lighter the sky background, the harder it will be to see the planets – so the right hand gives while the left hand taketh away!

How to know which is which.

The planets will change position each day, and as you will see from the charts below, the arrangement varies depending on where you are as well. So how do you know which is which?  Brightness will be your key. The brightest is Venus, the next brightest Jupiter, the next Mercury, and the dimmest Mars.  Mars will be the most difficult as it is both dim and low.

To get a feel for what a difference location makes, look at the next three charts. Note the latitudes – the first is for 42°N, the next for 26°N, and the last for 34° S. Also note that the first two are for 30 minutes before sunrise, while the last one is for an hour before sunrise.

30 minutes before sunrise – 42°N

Circle represents a 5-degree field of view. Most binoculars will show a bit more. Click image for larger view. Prepared from Starry Nights Pro screen shot.

Click here to download a printer-friendly version of this chart.

 30 minutes before sunrise – 26° N

Click here to download a printer-friendly version of this chart.One hour before sunrise - 34° SouthHere's the view from Sydney, Australia - note change in time and date. Circle represents a 5-degree field of view. Click image for a larger view. (Prepared from Starry Nights Pro software.)

Click here to download printer-friendly version of this chart.

Changing with date

These four  planets will provide an interesting, but challenging, tableau most of the month as the visual relationships change. Here’s a guide to those changes using charts  for every four days – all are for mid-northern latitudes and for about half an hour before sunrise.  No larger versions are provided, so don’t bother clicking on them and all are prepared from Starry Nights Pro screen shots.

Things to notice in the charts:

  • First Jupiter joins Venus and Mercury, then as it moves on, Venus, Mercury, and Mars form a trio.
  • Mercury never puts in a good appearance this month and it gets more difficult to see near the end of the month.
  • Jupiter does just the opposite, getting easier to see earlier in the morning as the month goes on.
  • On May 1 a slither of the waning crescent Moon is in the picture.
  • On May 29 the waning crescent Moon re-enters the tableau and will be present the rest of the month, though quite challenging on the last day. (The amount of Moon that is lit and its exact location will vary with your location.)

Notice the waning crescent Moon has entered the picture? It will be here three days, the last near Mercury.

Planet summary for May

Mercury – It is visible all month, but so close to the Sun and horizon you’ll need binoculars to spot it.

Venus – How can you miss it at magnitude -3.4?  Easy. It too is getting close to the Sun.  But look at the right time and you’ll see it and with the naked eye.

Mars – Very tiny and very dim right now because it’s about as far away from Earth as it can get and also is challenged by the pre-dawn twilight. But at least Jupiter will be of help early in the month in finding Mars.

Jupiter – Assuming you can find it, will guide you to Mars because Jupiter, though visible only during twilight, is comparatively bright.

Saturn – You can’t miss it – it’s the one planet high in the southeast and south in the evening – not morning – sky.  It is still visible in the west in the early morning hours. It sets as the pre-dawn planet show begins.

Uranus – A real challenge for binocular users.

Neptune – Even more of a challenge and as with Uranus binoculars are an absolute must.

Pluto -Hey, I mention it because it’s there – but this takes a fairly large telescope, a good chart, and a lot of patience. Since this post is aimed primarily at those using the naked eye and binoculars, I won’t mention it again – just kind of fun to know it’s out there with the rest of the gang in the pre-dawn sky even if its status has been demoted to dwarf planet.

Events December 2010: Eclipse of the Moon, Great Geminid meteors, and planets at all hours!

Lunar Eclipse Update – December 21, 2010 – 11 am EST – I fear much of the lunar eclipse reporting  – and photos –  doesn’t capture the real wonder  of what is going on – the up-the-down-escalator motion of the Moon through Earth’s shadow.

My friends Dom and Daphne from Australia, who were here observing with us in October, had a very special view of the eclipsed Moon, that does drive this home and have created a wonderful, online slideshow so we can see what they saw.  The for their view is the Moon was just emerging from totality as it rose in their eastern sky at sunset.  What make their report  special is the nearness to the eastern horizon of the Moon and the  proximity of all this to sunset so that the Earth’s shadow is actually tangible to us, along with the Belt of Venus, in the Eastern sky.

So take special note of the first shot that looks east where the shadow and the belt of Venus are.  Then watch as the Moon drops out of that shadow, diving towards the ocean – the eastern horizon. Also note the curvature of the Earth’s shadow on the moon – something that told the Greeks, long before Columbus, that the Earth was round.

What this drives home for me is that we  are seeing the shadow of the Earth darken the skynear the horizon to the east, as we always do right after sunset and – since we’re on the Earth – that shadow is huge from our perspective. Yet, out in the vicinity  of the Moon the shadow is only about 6,000 miles in diameter. At that distance, 6,000 miles would cover about a degree and a half of our sky – just three times the apparent diameter of the Moon – and so we see  the Moon appear to drop down out of that shadow – that is the Moon is moving eastward towards the horizon, while the whole show – Earth’s shadow and the Moon appear to be moving westward as the Earth turns.

Simply wonderful!  we all know the textvook explanation, but nothing beats seeing it live and the next best thing is to get a fine report of it such as the slide show Daphne put together – enjoy!



Lunar Eclipse Update – December 21, 2010 – 7 am EST Lot’s of reports with splendid photos of the eclipse showing a very red Moon as happens when our upper atmosphere is clear can be found on today’s Spaceweather.com. Go there and explore.  Although I love to observe without aid of cameras and computers, I also loved this report and photos from Bill Williams, an amateur in Florida. Bill wrote:

“I robotically controlled my telescope (14.5-inch RCOS) and camera (Apogee U16M) remotely 307 miles away at the Chiefland Astronomy Village using the internet. I transferred the data back to Boca Raton and processed it. Is this a great hobby or what?!”

To see his pictures go here.

Lunar Eclipse Update – December 21, 2010 – 3 am EST – Bt was cloudy here in Westport, MA, but there were several Web cameras available from various locations, though most of the ones I checked were being overwhelmed by the number of people looking for a live feed showing the eclipse.

I did find the one pictured below and although it sometimes stood still, it really did give a sense of being there. Here are some screen shots of the “live” action I could see.  I should note, that while we had light snow all day, and the sky was totally overcast, before the eclipse both the sky and the night in general were very light. The full Moon shone through the clouds and bounced off the fresh snow.  By totality, however,  it was very dark – not because of heavier clouds, of course, but because the Moon wasn’t shining through the high thin overcast any more. Very dramatic change I hadn’t anticipated. Here are the screen captures of one web cast.

Click on image for larger view. In the last image of Moon the folks web casting this had changed their camera settings so it was more sensitive to the light of the eclipsed Moon.

Orrinal post on December events follows:

It’s been three years since North America was treated to a total eclipse of the Moon – and it will be more than three years until we get another chance like this! That’s a long time between lunar eclipses, so let’s put clear weather on our holiday wish list for the night of December 20/21 when there will be a terrific total eclipse!

And that’s not all – with the right weather December could be a classic month for sleep deprivation with two great early morning events, plus other cool stuff happening at more reasonable hours, so this post is divided into three parts:

Best lunar eclipse in years! December 20/21, 2010

Click image for larger view.

Yep, you folks on the East Coast are reading that correctly – this is a morning event for us, but before you write it off, read on. I have a “half-is-much-more- than-50-per-cent” eclipse plan that you might want to try. The West Coast gets a break – an eclipse of the Moon happens at the same instant for everyone, but since we live in different time zones that instant occurs at different local times. So for the West Coast, the Moon turns into the Great Pumpkin just before midnight Pacific Standard Time. Oh – and if you’re on the East Coast of Australia – say Sydney? Well, you don’t miss out entirely. You get treated to the rather eerie spectacle of the Moon rising while already totally eclipsed. That will mean your first eclipse challenge will be to find the Moon! And all of this takes place in the most fabulous section of sky imaginable – right in the middle of some of the brightest constellations – Orion, Gemini, Taurus, and friends. And of course, these will be washed out by the full Moon prior to the eclipse, but during the eclipse they’ll come out in their full glory and the darkened Moon will occult a star or two as it journeys eastward. What a show! Study the map below to see if the eclipse is visible form your section of the world.

Click on image for a larger view.

And here is the eclipse sequence in Greenwich Mean Time so you can figure out how that relates to your time zone.

Click on image for larger view.

All these wonderful graphics are courtesy of Fred Espenak, www.MrEclipse.com) / CC BY-NC-ND 3.0 who has a terrific eclipse web site with lots of details about this eclipse and eclipses in general.

My half-is-much-more-than-50-per-cent plan

The real fun of an eclipse is in seeing the cover up – or uncovering – while at the same time watching the changing sky. I’m for seeing the whole show and if the weather gods cooperate, I plan to. But, I’m retired and seldom sleep more than four hours at a time, so mornings are no problem for me. Others have jobs to do and need their sleep. If that were my situation, I would try to carve out two hours and dedicate them to eclipse watching. That way I could get a real sense of the eclipse, while minimizing sleep loss. I figure if you see half of it, it’s almost as good as seeing the whole thing. So using the EST times I would make it a point to go out some time in the early evening for a few minutes just to appreciate the full Moon and note how it has washed out all but the brightest stars. Then I’d set my alarm for about 1:15 am and pop out to see the onset of the partial eclipse, which starts at 1:33 am. Again, note how the Moon is washing out most of the bright stars, even though it’s now fully into the penumbra – the weak part of the Earth’s shadow – and starting to enter the umbra. I’d stick it out to totality which begins at 2:41 am, take the next 20 minutes to enjoy the full glory of the stars with a totally eclipsed Moon, then be back to bed shortly after 3 am – thus losing about two hours sleep.

Of course you could work the same thing on the other side of the eclipse. Go to bed early and then get up about 3:15 am. If you’re out by 3:30 am, that will give you time to locate and appreciate the fully eclipsed Moon – note on the star charts below where it will be then – then watch it emerge from the Earth’s shadow starting at 3:53 am and over the next hour wash out more and more of the stars until totality ends at 5:01 am.

Or the-heck-with-sleep-plan, bring on the show!

Hey – one complete total eclipse in nearly six years – are you really going to let a little sleep deprivation steal the show? I’m not. This eclipse has me really psyched for several reasons. First, this is a real dry period between eclipses. There is one next June 15, but North America misses that one entirely. Next December (December 10, 2011) there’s another, and this one can be seen in part by those on the West Coast of North America. But the next full show for all of North America is not until April 14-15, 2014.

Another thing I like about this eclipse is it comes near the time of the winter solstice – 6:38pm, December 21,2010 – and that means the full Moon will be very high in our sky. The full Moon always rises opposite the Sun – so as the winter Sun sets in the southwest, the full Moon will rise in the northeast and travel high overhead.

A third thing I like is where, exactly, in the sky the Moon will be – it’s right in the middle of the Winter Hexagon – an area of sky that includes some of the brightest stars we see and most dramatic asterisms. In fact, the constellation that nearly everyone knows is Orion, and on eclipse night it’s going to look like Orion’s balancing the Moon on the end of his raised club! No kidding. Maybe we should think of that club as a torch for this night. Take a look!

Here's the Moon poised near the end of Orion's club just before the eclipse begins. Of course the Moon will drown out all but the brightest stars in Orion, but once totality begins most of these stars should be visible. (Starry Nights Pro screenshot.)

Is that cool? But wait, there’s more!

I admit I can’t spend hours looking at an eclipsed Moon – especially when there are so many other things to see in the surrounding sky. So by all means, bring your binoculars or a small telescope to this event. I’ll be using a telescope, but here I’ll stick to describing the naked eye and binocular sights.

Winter Hexagon and other things to look for as the moon gets darker and the stars come out. (Modified Starry Nights Pro screenshot.)

Click here for a printer-friendly version of the above chart.

The Winter Hexagon is a wonderful region of night sky, alive with a wide variety of sights. The stars that form it are among the brightest, starting with Sirius, the brightest star in the northern celestial hemisphere and at 8 light years, one of our closest companions. Procyon plays the “Little Dog” to the Sirius “Big Dog” – Sirius is the brightest star in Canis Major, Procyon the brightest star in Canis Minor. Castor and Pollux, the heavenly twins, anchor the next corner of the hexagon; then comes brilliant Capella, followed by the orange-tinted Aldebaran – the “bull’s eye” – and finally, the icy blue star at Orion’s left foot, Rigel. The best binocular sites in this area start with the Pleiades star cluster and its close neighbor, the Hyades cluster. (See the “look east” post for December for more about these two.) Orion’s Belt – the three bright stars in a row – slashes across the celestial equator and also is a wonderful, star-rich area to explore with binoculars. Finally, there’s the Great Orion Nebula – M42 – in the giant’s sword that hangs below his belt. Binoculars will show a little cloud in the middle of the sword that is an incredible region of gas and dust where stars are being born. Of course to see all this at its best you need to wait for totality at 2:41 am.

With binoculars or telescope

Obviously you can look at mountains, craters, and seas on the Moon and watch as they each get caught in the Earth’s shadow. But what I think will be most fun is to note the eastward motion of the moon by looking at its leading edge – the dark edge – and watch as one star after another gets snuffed out by the Moon. Now these stars will be more difficult to see during the partial phase, but the darker the moon gets, the easier it will be to see this happen and thus get a real sense that the Moon is indeed traveling around us. The Moon, like everything else in the sky, will appear to move from east to west. But at the same time, its motion around the Earth causes it to move eastward against the backdrop of distant stars. Once totally eclipsed, these “occultations” should be very easy to see.

The following video is a simulation made with Starry Nights Pro software. It shows the view from my location at 42 degrees north. Your view of the Moon – and which stars it occults – will depend on your latitude -so unless you’re within about 10 degrees of me either direction, you should take this simulation as illustrating what to expect in general, but the specific stars will differ. The brightest star occulted near the start is magnitude 7 HIP27698 – which should be visible in binoculars, if not at the start, certainly later when it pops out of the other side from behind a fully eclipsed Moon. The dimmest shown are about magnitude 12 and only visible in telescopes of the size most amateur astronomers use.

Oh – and if you stay up until the end of the eclipse, be sure to take a look at Saturn about 30 degrees high in the southeast and just five degrees from the beautiful double star Porrima. As always, it’s a grand show in any size telescope and now its rings are well displayed – the last couple of years they haven’t been. Below and to the left, Venus will be about six degrees above the eastern horizon and outshining everything except the Moon. Porrima, by the way, is an exquisite, but challenging double for small telescopes that’s getting a little easier to split every month as the two nearly identical stars move farther apart in their orbits.

A Geminids Storm! December 13/14 2010

This could be the best meteor shower of the year, especially for residents on the East Coast of North America – though it should be very good across the country.

The Geminids weren’t discovered until 1862, and when they were, they were more a meteor sprinkle, than a meteor shower. In 1877 astronomers were recording about 14 per hour. That’s wimpy. The Zenith Hourly Rate (ZHR) for the Perseids is 120. But a funny thing happened on the way to 2010 – the Geminids just kept getting better. In the 1930s the rate climbed to 50, was 60 per hour in the next two decades, and about 80 for the remainder of the century. But the respected “Observer’s Handbook 2010” of the Royal Astronomical Society of Canada puts the rate for this year at 120 – tied with the Perseids – and some say it could go higher!

Now before you get salivating to go out on a cold December night and lie in a lounge chair, let me set the record straight on “zenith hourly rate.” This is the number that’s usually quoted in various accounts – but most of the time this rate is mentioned it’s not explained and it leaves too many people with false hopes – especially those living in light-polluted areas, which is most of us. This rate is for ideal conditions, and I’ve never been lucky enough to have those ideal conditions. I would be tickled pink if I averaged one meteor per minute from a very dark site – the best I can do near home. Here’s how ZHR is defined in the Handbook:

Zenith Hourly Rate (ZHR) defined as the number of meteors a single average observer would see if the radiant were directly overhead and the sky dark and transparent with a limiting stellar magnitude of +6.5 (conditions that are rarely met in reality.)

That last phrase could also be written as “never in my lifetime!” 😉 I consider my skies super when the limiting magnitude is 5.5. Now I’m not a dedicated meteor shower watcher – but I’ve certainly been out there many nights over the years and generally have had very enjoyable meteor observing sessions – but seldom anything like what people report from the rare ideal site. But then – to have all the astronomical conditions just right is rare enough – yet that’s what this year’s Geminids could deliver, particularly for folks in the eastern half of the country. (As you move west there will be more interference from the Moon at the predicted shower peak time, but the Geminids still should put on a terrific display. The Moon will be low and just past first quarter.)

Oh – and for the radiant of this shower to be directly overhead here? The radiant – the general area where the meteors appear to radiate from – is a point less than two degrees from the bright star Castor and will be as high as it gets in my sky at 2:42 am EST. That won’t be directly overhead – but it’s at about 79 degrees altitude which is close enough to call directly overhead. (Use the Winter Hexagon chart posted above to find Castor – it’s the bright star near the top and is identified in that chart.)

Now here’s the really great news – and it’s why if the weather is clear I will be out there from 1 am on watching for Geminids. The quarter moon – which won’t interfere too much with earlier observing, sets at 1:16 am EST locally. AND – the Geminids are forecast to reach their peak at about 2 am EST. Now these forecasts are seldom right on, but they’re usually good. And I still have fond memories of a Leonid shower near the start of this century which really was a shower – the best I’ve seen in my life. And I hope to top that with this year’s Geminids.

But if the early morning peak turns you off, don’t give up on observing the Geminids. Start observing about four or five hours after sunset and you still should see enough to make it worth your while.

Where to look? They can appear anywhere. But more will be nearer the radiant. During my observing time I plan to be lying flat on my back and looking straight up. And by the way – that one or two a minute? That’s an “average.” Don’t expect to see one or two every minute. You have to look up continuously. And while you can talk to a friend, don’t let your eyes drift from the sky. Do that for at least 30 minutes and you should come close to the average – which I hope will be about one a minute. And I would be real happy with one every couple of minutes.

Finally, if you do see any, note their color – Geminids can be any of several colors – and, of course, notice how the meteor traces back to the radiant point in the sky in the constellation of Gemini. If you see a particularly bright one – take your binoculars and look where it just flashed. You ‘ll have a good chance of seeing a trail, similar to the vapor trail of a jet.

One last note: I think of most meteor showers as comet dust. That is, the Earth is passing through the dusty remnants left by a comet as it got near the Sun. But the Geminids are a bit of a puzzle here. They are believed to be associated with an asteroid known as 3200 Phaethon – only some folks feel this is not an ordinary asteroid. In fact, it is a dead comet. The jury is still out – but whatever the source, it should sprinkle some pixie dust our way December 13/14, and I hope to catch my share.

And Planets at all Hours – Jupiter, Uranus, Saturn – even Mercury and Venus, with a cameo appearance by Mars

Planet-wise, the month starts out with a bang. Jupiter and Uranus are high to the south at sunset; Saturn is getting higher and higher in the pre-dawn sky; and on December 2 there’s a terrific little triangle about an hour before sunrise of the crescent Moon, brilliant Venus, and the guidepost star, Spica. meanwhile, off to the north is another bright guidepost star, Arcturus, and Saturn is well placed above the triangle. (The Moon has a similar conjunction with Venus in the pre-dawn sky of December 31.)

Click image for larger version. (Starry Nights Pro screenshot with labels added.)

Click here to download a printer-friendly version of this chart.

Binocular users can bag Uranus, the planet that about doubled the size of our solar system – the “Georgian Star.” (To learn more about Uranus, see the September post here.) Uranus can be seen with binoculars, assuming it’s well placed, any time – but it’s far easier to locate when it is right near a bright planet such as Jupiter. This is the third time this year it has come close to Jupiter, but don’t hold your breath for this to happen again soon! In other words, see it now! (Neptune went through a similar sequence last year – now it’s off to the southwest and harder to find, though if you want to look, there’s a finder chart at the Sky and Telescope Web site.)

Jupiter joins the party!

Uranus starts off the month about three degrees from Jupiter in a neat little triangle with two stars that are almost identical in brightness to the planet, which is magnitude 5.9 – 20 Piscium (5.5) and 24 Piscium (5.9). As the month goes on, Jupiter moves closer and closer until the end of the month when it’s actually inside this little triangle and less than a degree from Uranus. Here are some charts to help you pick out the distant planet from the much more distant stars that form a backdrop. The circle covers five degrees, a typical binocular field of view, though your binoculars may show more.

Click image for larger version. (Starry Nights Pro screenshot with labels added.)

Click here to download a printer-friendly version of the above chart.

Click image for larger version. (Starry Nights Pro screenshot with labels added.)

Click here to download a printer-friendly version of the above chart.

Click image for larger version. (Starry Nights Pro screenshot with labels added.)

Click here to download a printer-friendly version of the above chart.

The Mars/Mercury Challenge

Can you find these two planets in the bright twilight using binoculars? On December 13 if you have a location with a clear western horizon – and really clear skies, you can put this to the test. It’s detailed by Tony Flanders in Sky and Telescope for December. He suggests looking just after sunset, but he thinks the easiest time to spot them will come about half an hour after sunset. This is one of those familiar races where to see the object, you need a dark sky behind it, but as the sky gets darker, the objects gets closer to the horizon making it more difficult to see.

Actually, your success will really depend on the weather. Looking in the right place should be easy. At my latitude of 42 degrees north the Sun will set that day at azimuth 239 degrees – pretty much southwest. Half an hour later Mercury and Mars will be at azimuth 234 degrees – five degrees to the south of where the Sun set. So if it’s clear, I plan to watch the Sun set and note the spot on the horizon where it vanishes. I’ll give it about 10 minutes, then start scanning about one binocular field to the south of that spot. In 30 minutes Mars and Mercury should still be roughly three degrees above the horizon. So if I look one binocular field to the south of where the sun set and just above the horizon, my binoculars should show me two first magnitude “stars” – it should look like this.

Labels added to Starry Nights Pro screenshot.

Events October 2010 – A Primetime Comet and the King’s Moondance

Comet Hartley 2 is the big observing news for October 2010, but the King of Planets, Jupiter, also will be putting on a prime time show all month with its four dancing Galilean moons. (Jump to Jupiter details here.) Venus and Mars, while technically still visible, are quickly closing in on the Sun in the west. Mercury is diving back towards the Sun in the morning sky, and while Saturn emerges in the morning sky, it won’t be high enough for a decent view until near the end of the month.

Ah, but there’s that comet! A “dirty snowball” that meanders roughly between us and Jupiter as it circles the Sun every six years. Its orbit, according to this wonderful applet at the Jet Propulsion Lab, looks like this. Notice how close it is to our little space station Earth on October 7 – that’s a good thing!

The outer white circle is the orbit of Jupiter. Hartley’s elliptical orbit is represented by dark blue for that portion below the plane of the solar system - light blue for when it is above the plane. This snapshot shows its location during a prime observing opportunity October 7. However, it will be easy for those in mid-northern latitudes to find throughout the first couple of weeks of October. (Click image for larger version.)

So let’s start the month with Hartley 2. This tiny periodic comet will:

  • Come closer to Earth than it ever has before – just 11 million miles;
  • Be easily found by binocular users in prime time well away from the Sun – and may even reach naked eye visibility;
  • Will be visited by a US space craft November 4, 2010, for some close up images in the hopes of learning more about these fascinating objects.
  • Finally, there’s always the possibility that it won’t behave as predicted. It may be dimmer – it may be brighter – even a lot brighter. Probably not – but after dull and dim Comet Holmes shocked everyone by brightening overnight by a factor of about half a million times in October of 2007 – well, comets need watching!

Generally, comets become brightest as they near the Sun – but this also can make them tricky to see. It’s usually a race with two opposing forces conspiring to make life difficult for the observer: As the comet gets closer to the Sun, it gets brighter. But as it gets closer to the Sun it also gets lost in the twilight glow. Such comets are frequently at their best just after sunset, or just before sunrise. This will not be the case with Hartley 2. Comet Hartley 2 will be a prime time comet for Northern Hemisphere observers. Figure on getting your best views of it during the first two weeks of October at a convenient evening hour, such as 8 pm. And circle October 7 as an especially fun time to take a look if the weather gives you a break. What makes October 7 so special? Well, the comet happens to be passing a favorite deep sky object that is also easily visible in binoculars. In fact this object, the famous Double Cluster in Perseus, is relatively easy to find with binoculars and if you can find it, you should be able to spot the comet in the same field of view. Here’s a guide chart I’ve modified some from a Starry Nights Pro screen shot. Notice that the Double Cluster is conveniently placed between two familiar asterisms – the “W” of Cassiopeia and the “Bow” of Perseus. Careful scanning between those two should be enough to reveal it, though the big problem most newcomers have with recognizing deep sky objects with binoculars and small telescopes is they don’t know what they can expect to see. So first here’s what I consider a reasonable simulation of the appearance of the double cluster in typical, hand-held binoculars.

A typical view of the Double Cluster in binoculars? Well - I think this is a pretty close match. It's a slightly Photoshopped version of a Starry Nights Pro screen shot that I hope will give you an idea of what you should expect to see. Of course exactly what you see depends upon your skies, your binoculars, and your eyes! And if you look on the night of October 7, 2010, there should be an extra fuzzy object in the view - Comet Hartley. (The Double Cluster is two open clusters containing hundreds of relatively young stars about 7,000 light years away.)

And here’s the guide chart for finding the Double Cluster and Comet Hartley 2 during the first couple of weeks of October.

Finding Comet Hartley 2 the first couple of weeks in October 2010. Click image for larger view. (Prepared from Starry Nights Pro screen shot.)

As the chart above shows, September 30 would be a great time to look for this comet because it will be so near the Alpha star of Cassiopeia – the “W.” Each day it continues in a generally eastward direction. The red circle is a 5-degree field, typical for 10X50 binoculars. (Your binoculars may show a larger field of view.) The comet enters near the top of the circle on October 6, is at the position shown on October 7, and will be exiting the circle at the bottom (eastern side) on October 8. On October 12 it will be about four degrees north of Mirfak. Remember – to find north in the sky just draw a line between a star and Polaris – in this case between Mirfak and Polaris – Comet Hartley should be pretty close to such an imaginary line on October 12.

After that it will continue its eastward path, coming closest to the Earth on October 20. However, after the 12th the moon starts to come into play during prime time and for the next two weeks it will dominate the evening sky, its light making the comet and other faint objects more difficult to see. That’s why the first two weeks of the month are best for this event, but of course the comet can be found later and will continue to be a fairly easy telescope object right through November, though at that point it starts to favor Southern Hemisphere observers. By November it’s down below Orion moving towards Canis Minor and so isn’t high enough to see until around midnight. Still,  it should be fun to look at it November 4th at the same time the comet is on NASA’s “candid camera.” For a more detailed chart for finding it on other dates, go here.

Now why all the excitement about a comet? They have a long history of scaring people – of being signs of impending disaster – but of course that’s from the days when we knew much less about them than we do now. Observing a bright comet in 1957 is one of my first memories of the night sky. Later I got my start in free lance magazine writing when I introduced the readers of Popular Science to Comet Kohoutek – the “Comet of the Century.” Well it wasn’t. My writing career survived that since I was quoting reliable scientific authority, but it sure bruised my ego when Comet Kohoutek never developed to anything like what was predicted.

That was my most shocking comet until 2007. That’s when Comet Holmes suddenly burst on the scene – and I mean burst. One night it was an incredibly dim magnitude 17 object visible only to professional astronomers and amateurs with extremely large telescopes – and neither the professionals nor the amateurs were much interested in it. Such faint comets are fairly common, and this one had been seen on repeated visits since 1892. But in just a few nights it was easily seen with the naked eye. Amateur star gazers were dazzled. It was a bright, round cloud in the same general area of the sky as Hartley 2 will travel through this fall. Yet it was farther away – out beyond the orbit of Mars and oriented so that from Earth we were looking right down the barrel, so to speak. That is, it had a tail, but the tail of a comet always points away from the Sun and in this case it was pointing directly away from us.

That fuzzy blob just kept growing so that for a brief time it was actually the largest object in our solar system – though it was, of course, a big fluff ball consisting of next to nothing. And while scientists have their theories on how all this came about, no one is sure. The puzzles that continue to surround comets is why NASA, after visiting another periodic comet in 2005, decided to take a close look at this one as well. What will they see? Not much, I suspect. That is, not much in terms of what the average person will be able to interpret from the pictures. But presumably some more pieces of the comet puzzle will fall into place. As reported on Gary Kronk’s authoritative “Cometography” site – bookmark that one for future reference – here’s the plan:

The Deep Impact spacecraft, which studied periodic comet 9P/Tempel 1 in 2005, will examine 103P/Hartley 2 during the period of September 5 to November 25, 2010, as part of the EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) mission. The closest approach occurs on November 4, when the minimum distance to the comet will be only 620 miles (1000 kilometers). The spacecraft will use two telescopes with digital color cameras and an infrared spectrometer. The latter instrument will determine the chemical composition of outbursts of gas from the comet’s nucleus.

And what will we be looking at? Comet Hartley is small even for a comet – about three-quarters of a mile across. (In comparison Comet Tempel 1 is thought to be 8.7 by 2.5 miles in size.) The revised general description for comets these days is a dirty snowball with a crust. Think of it a moment. Comets are not just any old chunk of rock. Millions are thought to reside in the Oort Cloud out at the farthest reaches of our solar system – about one light year away. They are thought to be pure examples of the original material of the cloud of gas and dust from which we were all formed – yes, I mean you and I. Seeing a comet up close is roughly akin to the ultimate of finding something really cool in your grandparents’ attic! So don’t get them confused with the other rocks that tend to float around nearby. We call those asteroids, and we worry some about them colliding with the Earth because such a collision would produce a major disaster. And, of course, a collision with a comet even as small as Hartley 2 would produce a major disaster. But comets and asteroids, while looking similar when far away from the Sun, are really quite different beasts. The visit to Comet Hartley 2 will include no pyrotechnics – Deep Impact has done its thing as far as throwing stuff at comets is concerned. Still, this picture of the mission to Tempel 1 when we shot a probe into it gives you a feel for what a comet looks like close up. It will be interesting to compare this photo with what we see in early November.

The Tempel 1 mission included striking the comet with a spacecraft to cause an explosion and learn more about its makeup. From the NASA press release accompanying this picture: “This spectacular image of comet Tempel 1 was taken 67 seconds after it obliterated Deep Impact's impactor spacecraft. . .. The image reveals topographic features, including ridges, scalloped edges and possibly impact craters formed long ago.” CREDIT: NASA/JPL-Caltech/UMD

Meanwhile, out at Jupiter, the moons are doing their thing

An hour after sunset on October 1, Jupiter is already 15 degrees high in the eastern sky. It’s by far the brightest “star” in the east, so you can’t miss it. Each night it will a bit higher at the same time, and the higher it gets the easier it is to see detail and the moons using a telescope or binoculars. (Uranus is still nearby as well. If you want to try to spot it, see this post with charts from last month.)

Jupiter is a favorite sight in small telescopes – and to see the four Gallilean moons you really should use a telescope – any telescope. I have a tiny, 50mm “department store” telescope that mounted on an ordinary camera tripod does an excellent job showing the moons of Jupiter. It is possible to see them with binoculars if you have good eyesight and can hold the binoculars really steady – lean against a building, or better yet, mount them on a tripod.

Here’s a simulation of how the moons change position in a single evening. The changing tilt of the plane of the moons is due to the changing position of Jupiter in the night sky.

The moons shown at the start of the video are, from left to right, Callisto, Ganymede, Europa, and Io. The video simulation was made using Starry Nights Pro software.

They’re called the Galilean moons, of course, because Galileo discovered them four hundred years ago when he pointed a small telescope at the sky. The sight shook up the world! At that time most folks believed the Earth was at the center of the universe and everything revolved around it. A bit conceited, perhaps, but darn, watch the sky on any given night and it sure looks like we’re at the center of things! But here comes Professor Galileo with his new-fangled looking glass, and he points it at the bright “wandering star,” Jupiter, and what he sees is another world. Not only is it another world but a world with four little worlds clearly whirling around it! And of course he rushes right into print with this astounding discovery publishing his “Sidereus Nuncius” or “Starry Messenger” in March of 1610. Today many amateur astronomers enjoy studying details on this largest of planets. I love watching Jupiter’s four brightest moons. Here’s why:

  • You can see them with any small telescope – even binoculars if you can hold them really steady.
  • They do something! Most astronomical objects don’t change much over our lifetimes. Jupiter’s moons can go through significant changes in a single night as the video above shows.
  • These four bright moons played a major role in changing our view of the universe.
  • They even helped us determine the speed of light a couple of hundred years ago, something next to impossible to determine on Earth without modern, sophisticated instruments.
  • For the telescope user they:
  1. duck in and out of Jupiter’s shadow (eclipse)
  2. hide behind the planet and suddenly pop out (occultation)
  3. cross in front of the planet providing a challenge for telescope users to spot them (transit – this is what Io does in the above video)
  4. and from time to time they cast their shadows on the giant planet – shadows visible in a backyard telescope as perfect round circles
  • Hubble and modern spacecraft have shown us that Jupiter’s moons are full of surprises. No two are alike and all four are different than what scientists imagined before the spacecraft got out there and gave us an up-close and personal view.
  • All of which is incredibly awesome when you understand that the little lights you see moving with grace, precision, and predictability are complete worlds in themselves the size of our moon or larger. (Ganymede is about 1.5x the diameter of our moon.)


How do you know which moon is which?

If you want to know which of Jupiter’s moons is where on any given night, use this neat little online utility provided by Sky and Telescope magazine. Now the basics. Jupiter has 63 moons, but only four of them are easily seen in small telescopes. Here are their names – in order moving outward from the planet – and links to more details about each.

Oh – and about determining the speed of light. Think about it. I believe Galileo once took a stab at this by stationing observers facing one another from different mountain peaks. They then uncovered a lantern at a predetermined time. No luck. Light is much too fast for this kind of experiment. Hey – light could go completely around the Earth more than seven times in a second! But here’s how Jupiter’s moons helped determine the speed of light more than 300 years ago! These kinds of discoveries always leave me in awe at how brilliant the discoverers were and how precisely they were able to make observations with tools that were not nearly as good as the inexpensive telescopes available to anyone today. The account which follows can be read in full here. It is from a posting by Michael Fowler of the University of Virginia Physics Department. One more thing to appreciate as you watch Jupiter’s moons.

The first real measurement of the speed of light came about half a century later, in 1676, by a Danish astronomer, Ole Römer, working at the Paris Observatory. He had made a systematic study of Io, one of the moons of Jupiter, which was eclipsed by Jupiter at regular intervals, as Io went around Jupiter in a circular orbit at a steady rate. Actually, Römer found, for several months the eclipses lagged more and more behind the expected time, but then they began to pick up again. In September 1676, he correctly predicted that an eclipse on November 9 would be 10 minutes behind schedule. This was indeed the case, to the surprise of his skeptical colleagues at the Royal Observatory in Paris. Two weeks later, he told them what was happening: as the Earth and Jupiter moved in their orbits, the distance between them varied. The light from Io (actually reflected sunlight, of course) took time to reach the Earth, and took the longest time when the earth was furthest away. When the Earth was furthest from Jupiter, there was an extra distance for light to travel equal to the diameter of the Earth’s orbit compared with the point of closest approach. The observed eclipses were furthest behind the predicted times when the earth was furthest from Jupiter. From his observations, Römer concluded that light took about twenty-two minutes to cross the Earth’s orbit. This was something of an overestimate, and a few years later Newton wrote in the Principia (Book I, section XIV): “For it is now certain from the phenomena of Jupiter’s satellites, confirmed by the observations of different astronomers, that light is propagated in succession (note: I think this means at finite speed) and requires about seven or eight minutes to travel from the sun to the earth.” This is essentially the correct value.

Less successful was an idea they had much later that they could solve the problem of finding one’s longitude – while at sea – by observing the moons of Jupiter. This was very seriously pursued because knowing longitude is critical to navigation and the accepted method involved using a very precise clock that kept correct time throughout a long sea voyage. It was hard enough to make a very precise clock – but one that retained its precision when subjected to the knocking about and unavoidable moisture that was part of any long voyage by sail? Nearly impossible. (See the wonderful book, “Longitude,” by Dava Sobel, for the story of how they did solve this.) But that said, as you watch the moons of Jupiter with a small telescope, try to imagine doing this on the heaving deck of a sailing ship with a telescope that is significantly cruder than the one you buy today! Then imagine that your life may depend on the result! Makes you appreciate the GPS if nothing else ;-)

So get out some night this month and take a close look at our neighbor, Jupiter. And if possible, see if you can see the moons. Newton is playing the tune, and the moons do the dance – music of the spheres indeed!


UPDATE – October 14, 2010 – Spent a nice hour  this morning (4 am – 5 am) with Comet Hartley 2 – well, too much of that time trying to figure out how to find it with the Orion 110ED which is mounted on a parallelogram mount in my observatory and gets kind of complicated to point near the zenith. But I found the comet in just 30 seconds of looking with the 15X70 Celestron binos. That was easy and the comet seemed significantly larger and brighter than it was in my other observations of the past week. In ease of finding with those binoculars I would put it about halfway between M33 and M31. It seemed larger in the binoculars, as well. It was not nearly so easy inthe 8X50 finder – but certainly clearly visible.

Once I figured out how to twist and turn the 110 so it was pointed at the right section of sky – this is a very rich area about 6 degrees east of Mirfak – it showed very nicely in the 110mm. Yes, I could see a tail. I drew the stra field and sketched the comet and I had the orientation of the tail correct – but I was not confident I was seeing the tail until I checked my sketch against the charts. In other words, the tail is faint. In binoculars the comet reminds me very much of Holmes – especially since this is the same region Holmes inhabited when it was quite bright. But Hartley is moving much, much faster.

With the binos it was simply a blob – a puff of smoke among – and overlapping – some faint stars. In the 110mm it took on a solid nucleus – not star-like – larger – and a clearly defined coma. I kept changing the estimate of the coma’s size as I went from a 24mm Panoptic to Naglers of 13, 7, and 3.5 – that last is 236X. With each increase in magnification my estimates got smaller – not because I was seeing less of the comet – it took magnification well- but because I tend to think and object is taking up a greater percentage of the eyepiece than it is. Once more my sketch came to the rescue. It was easy to compare it to the known starfield and get an accurate measurement of 9 minutes of arc across for the clearly visible coma. I would put what I felt I could identify as a tail at about two or three times that. Be interesting to see what the photos show. My estimates are strictly about what I can see with what I’m using under dark and transparent skies -the transparency being a 4 out of 5 with 3 being average.

It is really a morning object now, with the moon starting to  drown it out in the early evening.

UPDATE: October 7, 2010 -Comet Hartley 2 now visible in “normal”  binoculars! Last night it was bright enough for me to see  using 8X40 binoculars – significantly brighter than on October 2 when I last saw it. It was an easy target in 15X70 binoculars and I suspect that at this rate it will be reaching naked eye visibility – just barely – for those with really dark skies..  But even with small binoculars it’s still the kind of target that requires an   observer to have some experience  to find and see. For example, if you can find and see the large galaxy, M33, you certainly should be able to use the same instrument to see Hartley now.UPDATE: October 2, 2010  – While I would not discourage people from searching for Comet Hartley 2  right now, it is something that only experienced observers with dark skies will find easy to see at this moment. I have mag 5.5 skies and I could not see it last night while using 15X70 hand held binoculars when it was  about 50 degrees above the horizon in the early evening. I did see it with an 80mm telescope and it was visible to one of three new observers who were visiting me last night when we used a 6-inch refractor. I would rate it a bit more difficult to see than M110, the fainter of the companion galaxies to M31. 

Meanwhile, Spaceweather.com said early today that “some observers are reporting that comet 103P/Hartley 2 has reached the threshold of naked eye visibility.” I wrote them challenging those reports. No response, but I noticed that by 2 pm the earlier update had been taken down and a new one replaced it – one that makes no mention of “near naked eye visibility.

Sky and Telescope does report that it should brighten significantly over the coming week. I hope so. I worry about giving eager newcomers the wrong impression when we say – as I have done – that this is visible in binoculars. It may be in a  few days –  or to experienced observers with very dark skies right now – but not to more casual observers who have to cope with typical, suburban light pollution!  While Comet Hartley 2 makes its closest approach on October 20  and should be brightest then, it will be difficult to see at that time because it will be fairly low in the evening sky and a nearly full moon will be drowning it out. I suspect the best time to see it will be around October 12 before the Moon offers significant interference.  Perhaps then it will be visible to more casual observers using binoculars.

That said, it is an incredible sight in a large telescope.  I observed it with my 15-inch reflector last night and was just blown away to think that so small an object – about three-quarters of a mile across – could kick out such an incredible dust cloud that we can see it from such a distance. If Comet Hartley 2  was a huge rock on the Moon I would not have a prayer of seeing it at just 3/4 of a mile across, even with the 15-inch. But it is about 50 times farther away. I haven’t done the calculations, but that cloud of dust I’m looking at has to be quite huge and is reflecting an awful lot of sunlight to make it visible to me. That’s awesome!

June 2010 events: A month of surprises involving Jupiter, a comet, and maybe even some meteors!

Note: While many of the following events are visible throughout the world, the exact time and location in the sky can be dependent upon your latitude and longitude. Since I’m in the mid-northern latitudes (41.5N, 71.1W), specifics, where place-and-time-dependent, are calculated for this location.

Observing Jupiter and Uranus

June promises to be full of surprises, most revolving around getting up early to enjoy a summer dawn! I’m circling the weekend of June 12-13 on my calendar as special in terms of getting up early, and I’m hoping for a triple header: viewing Jupiter, finding Uranus, and seeing Comet McNaught. For the meteors, it will be June 23 and in the evening – though there’s a real big question mark around this event. Let’s start with a sure thing – Jupiter and Uranus.

You can’t miss Jupiter. It’s the brightest “star” in the southeast in our morning sky. You can easily miss Uranus. It’s barely naked eye visibility in the best – least light-polluted – locations and hard to pick out from true stars in the area. But on a morning in June finding Uranus should be an easy task with any decent pair of binoculars because Jupiter will guide you right to it.

It’s Jupiter that offers our first surprise for those who can turn a small telescope on it. Usually even the most modest telescope will show you two dark belts on Jupiter – but this June there’s no telling Jupiter missing bandexactly what you’ll see. Jupiter’s been hiding behind the Sun recently, but when it emerged in May it surprised planetary observers by displaying just one of its major trademark dark bands. The other had vanished!

If you have a small telescope and point it towards Jupiter on a June morning will you see it this way? Can’t say. That’s why it will be a surprise. Veteran observers think the second band could come back quite quickly – in just a week’s time, for example. They say this sort of thing is rare but has happened before. One theory is that high, thin, light-colored clouds are covering the band, and these clouds may vanish without warning – just as they appeared without warning.

Jupiter is second only to Saturn in its appeal to small telescope users, not only because of its bands, but because of the constant dance of its four Galilean Moons, which you can detect if you can manage to hold even modest binoculars, such as 10X50s, steady. And Jupiter this year will be doing an even grander dance with its outer cousin, Uranus. The two gas giants come quite close to one another – as viewed from Earth – three times in the next seven months, the first being in June. That means Uranus, usually a difficult object to find because it is so faint, will be an easy target for binocular and small telescope users – though its disc is so small it will hardly show except in a telescope at high power.

Here are a couple of images giving you the position of the two planets early in the month and near the end of the month.


Click image for a larger view. Image developed from "Starry Nights Pro" screen shot.

For a printer-friendly version of the appropriate chart for on or near June 6, 2010, click here.

For a printer-friendly version of the appropriate chart for on or near June 30, 2010, click here.

A good project would be to take the print out of the first chart (June 6) and mark the position of each planet when observed about once a week. You’ll notice that both drift to the east (left) against the background of stars, but Jupiter’s progress appears much faster because it is so much closer to us. That would help you appreciate the fact that when Uranus was discovered March 13, 1781, by the English astronomer William Herschel, it effectively doubled the size of our solar system! (And if you don’t want to get up early several mornings to actually see this, just study the charts above, but be sure to click on them to see the larger version. 😉 For more on Uranus see the May events entry.

The two planets come closest on June 8 when they are less than half a degree apart. However, any time during the month they will easily fit in the same binocular field of view. I’m aiming for observing on or near the 12th simply because it’s a weekend, and since there’s no Moon in the sky to drown things out with its glare, that will also be a good time to spot the comet.

Seeing Comet McNaught at its best

Comets are notoriously unpredictable and catching them at their best is a game you play, trying to balance the time when the comet is close to the Sun – and thus usually brightest – against the approach of dawn, which lightens the sky behind the comet as it gets closer to the Sun and thus makes it more difficult to see.

Northern hemisphere observers are overdue for a nice comet and McNaught (C/2009 R1) could be it. Astronomy magazine thinks it may reach naked-eye brightness with a distinct tail. Sky and Telescope seems a bit more cautious in its prediction, but still thinks it will be very nice in mid-June. In 2007 another Comet McNaught (C/2006 P1) put on an absolutely spectacular display for southern hemisphere observers, becoming the brightest comet in 40 years seen from anywhere on Earth. Sadly, for those in mid-northern latitudes the show was nowhere near as good and was so brief many missed it. I was lucky to catch it, but against strong twilight, so it didn’t show at its best. I took this shot of Comet McNaught over Horseneck Beach in Westport on January 11, 2007.


Bren and I saw an earlier Comet McNaught in strong twilight and amidst clouds in 2007 shortly after sunset.

A recent study, however, has found that Comet McNaught was not only a spectacular sight from the southern hemisphere, but also probably the largest comet on record.

It’s fairly safe to say this Comet McNaught will not be nearly as spectacular – but it could be quite nice, especially in binoculars, and it should be easy to find as it will be going past some well-known stars. In fact on the morning of the 12th it will be right between Algol (the Demon Star) and Mirfak, brightest star in the constellation Perseus. Here’s a chart – but take the show of the comet’s tail as simply a rough indicator of the tail’s direction. I doubt it will be this large. (Starry Nights software, from which this chart was derived, shows all comet tails about the same length.)

Comet McNaught 2010

Click image for larger version. Chart derived from "Starry Nights Pro" software.

For a printer-friendly version of this chart, click here

As with the Jupiter/Uranus event, Comet McNaught should be visible much of the month. But early in the month it will be dimmer, and later in the month it will be so close to the Sun that the dawn twilight will drown it out. The middle of the month seems like the best bet for catching the comet when it’s quite bright and will be high enough in the sky to see well during a time period when the sky behind it is fully dark.

The beginning of astronomical twilight is when the sky starts to brighten and continues to do so right up through sunrise. For my area – and other mid-northern latitudes – astronomical twilight starts about 3 am in mid-June, more than two hours before sunrise. (Tables for astronomical twilight times for your area can be easily created at the U.S. Naval Observatory site here.) My plan, weather permitting, is to go out on Saturday morning, June 12, to a local observing sight that has a beautifully clear and dark eastern horizon, and to be there by 2:30 am EDT. That will give me an opportunity to see Comet McNaught when it is about 15 degrees above the northeastern horizon. I expect to have a good view right up through 3:30 am – after that I expect the interference from the approaching dawn to become serious. (That’s the date of new Moon, so it will offer no interference for several days either side of this date.)

But again, comets just aren’t that predictable. Back in 1973 I published a cover story in Popular Science quoting experts who predicted that Comet Kohoutek would be the “comet of the century.” It was no such thing and I was embarrassed! And the most exciting comet of recent years for me was Comet Holmes in 2007, which suddenly – and inexplicably – broke into naked eye glory when no one was expecting it to do any such thing.

What can be done with accuracy is to predict when and where you can expect to see Comet McNaught. Those predictions you can trust. And you should begin your search with the naked eye, but I suspect binoculars will give you your first view, and it may take a small telescope to give you a really decent look at it.


  • For an orbit diagram of the current Comet McNaught see this page.
  • This Comet McNaught is the 56th comet discovered by this man. Why so many? Well, for the past five years or so it’s been his job to find comets  that may pose a threat to Earth and he has the tools to do it. Go here to learn more.

Catching the elusive Bootid meteors

If anything in amateur astronomy seems riskier than making predictions about comets, it’s making predictions about meteor showers – especially unusual ones that flare up on rare occasions. But Astronomy magazine is carrying a prediction that on the night of June 26 – and we’re talking the more comfortable evening hours now – we could get quite a display.

It reports that the International Meteor Association predicts that the peak of this shower could occur on June 23/24 between 7 pm and midnight EDT. Well, of course that means this favors the East Coast and even then, it may peak while it is still light, since you won’t have complete darkness until after 10 pm.

Frankly, I’m very skeptical about this one, but if it’s clear that night I’ll do some observing of double stars and keep an eye out for meteors at the same time. The problem is simple: at 10 pm the Moon, just a couple of days short of full, will be low in the southern sky, but still high enough so I think it will drown out many of the meteors. So what we have here is a prediction that a normally quiet “shower” may suddenly have a real outburst worth seeing – but that outburst could come during daylight or twilight, and if it comes during full darkness it will be competing with bright moonlight. That just doesn’t seem all that promising. But then, what can you lose being out on a warm June evening with clear skies, bright moon, and and fireflies? And now you know you may get lucky and see some bright meteors as well – maybe a whole lot of meteors 😉

June’s Calendar – a chronology and review

You have the highlights above – here’s a summary of them, along with some additional June events, in chronological order.

  • June 4 – Last quarter Moon
  • June 5,6,7,8 – Watch Mars pass close to Regulus – note color difference! (Mars is just a tad brighter.)
  • June 6 – Good time to start your search for Uranus and Comet McNaught
  • June 12 – New Moon – prime weekend for an early morning expedition to see Jupiter, Uranus, and Comet McNaught
  • June 14 – Brilliant Venus just above a thin crescent Moon – nice!
  • June 19, 20 – Venus is just 1 degree from the Beehive – use binoculars to see the stars near this most brilliant planet.
  • June 21 – The Summer Solstice – and shortest night of the year. Comet McNaught should be getting quite difficult to see by now.
  • June 23 – Cross your fingers and hope for some spectacular meteors appearing to radiate from Bootes still high in the evening sky.
  • June 26 – Full Moon – and a partial lunar eclipse in the morning sky for folks in western North America and points west.

Jupiter’s back-and-forth wanderings

On October 1, 2009 a nearly full moon joins Jupiter, Uranus, and Neptune in the southeast as shown here about an hour after sunset as seen from latitude 42 degrees north and longitude 71 degrees west. Chart from StrayyN oghts Pro software. Click for larger image.  .

On October 1, 2009 a nearly full moon joins Jupiter, Uranus, and Neptune in the southeast as shown here about an hour after sunset. (Jupiter is made large to indicate its relative brightness - ut it will look like a very bright star - not a small moon!) This is how the sky appears from latitude 42 degrees north and longitude 71 degrees west. Chart from Starry Nights Pro software. Click for larger image.

The idea here is simple – connect what we can see in the sky this month with what’s actually going on. We’ll do this by watching Jupiter, the easiest object to find right now since it is the brightest “star” fairly high in the southeast shortly after sunset.

With just a few quick checks with binoculars we should be able to track the movement of Jupiter in relation to a bright, nearby star. You should start this project on or before October 1, 2009 if at all possible and plan to observe two or more nights between your start time and October 13. Then observe again in about a week and again near the end of the month.Your first couple of checks should show Jupiter in “retrograde” moving westward among the background stars. Your next two checks should show Juputer has resumed it’s normal eastward movement.

Use the following chart as both your guide and your log. That is, click on it to get a version you can print, take out under the stars, and record your observations on with a pencil.

Click for larger version, suitable for printing.

Click for larger version, suitable for printing.

So why does Jupiter appear to first go one way, then the other? Afterall, it isn’t really doing that, is it? Like the other planets – and us – it’s simply continuing a steady, eastward journey around the Sun. But so are we – and we are moving much faster because we’re much closer to the Sun. So what you are seeing is partly the movement of Jupiter – but also the apparent change in its position caused by our rapidly changing position.

I made the following animation from Solar System Live charts. It shows how Jupiter’s position changes slowly in relation to Earth and the other planets, particularly Neptune. The animation starts with September 1, 2009  and moves a month at a time for six months. The arrow shows our changing view of Jupiter with relation to Neptune, a much more distant – and even more slowly moving, planet. Notice that in late December Jupiter makes another close approach to Neptune – the third this year – which will make especially easy at that time to find this distant and faint planet. Right now you can use the chart above to track it down – it would be just visible in binoculars on a moonless night.


So let’s review the movements we’re dealing with here.

1. The daily rotation of the Earth causes Jupiter to appear to rise inthe east and move westward as the night progresses.

2. The revolution of the Eartha round the sun at a much higher speed than Jupiter makes it so that for some time the huge planet appears to be moving westward in relation to background stars and the more distant planet Jupiter. That apparent westward motion comes to a stop October 13, 2009.

3. Jupiter’s own motion is more apparent after October 13, as it appears to move eastward against the background stars. This general motion will carry it about 30 degrees eastward – very close to where Uranus can be found now – in about a year. It takes Jupiter almost 12 of our years to make a complete circuit of the sky.

Prime Time observing for September 2009 – a square, a couch, dancing moons, and more!

Please note: All charts with this post are for observers in mid-nothern latitudes centered on 40° N. If you are 10 or more degrees south or north of that – or if you’re not sure of your latitude – please go here to make your own custom star charts.

Our focus as always is the eastern sky, 45 minutes after sunset, where in September 2009 we’ll find a brilliant Jupiter whose moons play a fascinating game of hide and seek. But our main goal will be to locate and remember  this month’s  two new asterisms the Great (empty) Square and Andromeda’s Couch.

Let’s start with Jupiter, though, because no prime time observer can fail to find Jupiter in the eastern sky starting about half an hour after sunset – there’s simply nothing brighter except the Sun and Moon – well nothing brighter in the eastern early evening sky.  Venus gets brighter than Jupiter, but it never appears in the eastern sky after sunset, though it is in the eastern sky these September mornings an hour or so before sunrise. If you’re one who likes to be up then, be sure to take a look – you can’t miss it!

Though not visible to the naked eye, what’s most fascinating about Jupiter is its four brightest moons. Yes, they look a lot like little stars, even in the telescope, but they are in a rough line with the planet’s mid-section and they continuously change positions around the planet from night to night. In fact these changes can be seen over the course of an hour or so, though at the least you need good binoculars that are held very steady in order to see them. Any small telescope, however, should reveal them easily. For an introduction to observing these four moons see the video and text here. This describes moon events for an extraordinary evening – September 2/3, 2009 – but at some time on many evenings you can observe one or two such events, so even if you miss the events of September 2/3, watching the animation and reading this should help you understand similar events that happen quite often whenever Jupiter is visible.

Of course Jupiter is not going to help you learn the rest of the night sky because like all planets it is constantly changing its position relative to the background stars. But our two bright asterisms for September will help and they are as simple as they come – a square with an arc of three bright stars attached to it.

Click chart for a much larger version.

Click chart for a much larger version.

The first is known as the “Great Square.” I call it the “Great (empty)  Square” because the area inside it is almost completely empty of other naked-eye stars.  The other asterism ties to it like the tail of a kite flying sideways.  It streams off one corner and I think of it as “Andromeda’s Couch.” Of course this is just my memory device – others would simply call this “Andromeda” because that’s the name of the constellation it dominates. I have difficulty seeing the lovely maiden, chained to a rock by looking at these stars and their companions, however. Like most constellations, with Andromeda you need a huge imagination to see the figure these stars represented to the ancients. But knowing Andromeda was a lovely woman who was rescued by Perseus, I like to think of this graceful arc of stars as her couch.  That said, notice three things about it:

1. The bright star at the right – southern – end is also a corner of the Great Square. In fact, it is the brightest star of the four that make up the square, but only by a little.

2. The three stars are pretty equally spaced. Hold your fist at arms length and it should easily fit in the gap between the stars which means there are 10-15 degrees between each star. That’s similar to the spacing between stars inthe Square.

3. There’s another dimmer, but fairly bright star, between the first star ( the one at the corner of the Square)  and the middle one.

And where’s the hero Perseus? he should be nearby, right? Well he’s on his way, rising in the northeast after Cassiopeia, but we’ll leave him for next month when he’s more easily seen.

Looking north

Meanwhile, for those in the northern hemisphere, the bright stars circling Polaris and always visible are well represented this month with the Big Dipper starting to move towards the horizon in the northwest and the “W” of Cassiopeia starting to take the dominant role in the northeast opposite it.

Click chart for a larger image. Northern skies as seen from about 40° N latitude in mid-September..

Click chart for a larger image. Northern skies as seen from about 40° N latitude in mid-September..

Our chart shows the northern celestial pole region about 90 minutes after sunset when skies are about as dark as they get. Will you see all these stars? Depends. First, on how much light pollution there is where you observe. Second, on how well your eyes are dark adapted. You must avoid white light for at least 15 minutes – better still, half an hour – if you wish to see the fainter stars. If you want to test how good your skies and night vision are, look at the Little Dipper. In light-polluted suburbs you will probably see just the three brightest stars. In good rural conditions you should see all seven.  And if you can see them, then this is a good opportunity to try to trace out Draco, one of a handful of constellations whose connect-the-dots pattern actually suggests the mythological figure of a dragon.  I love Draco, but quite honestly, I have to look for it – it doesn’t jump out at me the way the Big Dipper and the “W” do.  And as far as learning the sky – well, you learn the “W,” the Big Dipper and Polaris so you can then find stuff like Draco when you want to find it.

The arrows on the chart indicate the general direction in which the sky appears to move. Stay out an hour and this motion should become obvious to you.

. . . and the rest of the guideposts?

If you’ve located the new September asterisms then it’s time to check for the more familiar ones you might already know, assuming you have been studying the sky month by month.  (If this is your first month, you can skip this section. ) So here are the guidepost stars and asterisms still visible in our September skies.

  • The Summer Triangle is now high overhead, though still favoring the east. Vega, its brightest member, reaches its highest point about an hour after sunset and moves into the western sky. Altair and Deneb are still a bit east, but will cross the meridian within about three hours of sunset.
  • The “Teapot,” marking the area of the Milky Way approaching the center of our galaxy, is due south about an hour after sunset. Well into the southwest you’ll find the red star Antares that marks the heart of the Scorpion.
  • Arcturus (remember, follow the arc of the Big Dipper’s handle to Arcturus) is due west and about 25 degrees above the horizon as twilight ends.
  • The Keystone of Hercules and the circlet that marks the Northern Crown can both be found high in the western sky by tracing a line between Vega and Arcturus.

. . . our journey and September’s planets (2009)

In the course of a night you can still get a glimpse at all the planets – technically – but the truth is both Saturn and Mercury are very difficult to see this month, and Pluto is always just a faint speck visible in large amateur telescopes. Jupiter, as we’ve noted, dominates the evening sky in the southeast. Nearby – visible in binoculars or small telescopes – is Neptune. And an hour or so later, if you want to track it down with binoculars, Uranus will make a good test of your star-hopping skills.  In the morning sky both Mars and Venus are prominent, though Venus gets closer to the Sun throughout the month. At the start of the month Venus rises about three hours before the Sun – by the end of the month this is cut to about two hours – but even in twilight it is so bright it’s hard to miss.

Charts to help you find the  planets follow, but first, let’s look at the solar system from the perspective of someone in a spaceship hovering above it. This shows us where we are in our journey around the Sun and also gives us a chance to examine where the other planets are in relation to us. See if you can translate this perspective into what we see in our sky. The chart below was created with the Solar System Live capability found here. I added the arrows in Photoshop Elements simply to indicate the horizon and directions relating to the earth’s rotation on its axis.

Click image for larger view. Arrows indicate the western and eastern horizons at sunset on September 15, 2009. Smaller arrows show the direction these horizons move at the earth turns on its axis in the course of the night.

Click image for larger view. Arrows indicate the western and eastern horizons at sunset on September 15, 2009. Smaller arrows show the direction these horizons move as the earth turns on its axis in the course of the night. (Planets are not drawn to scale.)

Looking at the horizon line going out to the west – left – you can see that at sunset Saturn is nearly on the horizon.  Use the arrow going to the east (right) and you can see Uranus isn’t quite visible in our night sky at sunset, but Jupiter, Neptune, and Pluto are well beyond the eastern horizon.  Draw an imaginary line from Earth through Jupiter and you’ll see it comes near Neptune – which is why Neptune appears relatively close to Jupiter in our night sky this month, though you’ll need binoculars to find it. (Notice also that Neptune, while a giant planet, is more than twice the distance from the Sun as Jupiter – which is why it is so dim and small in our night sky while Jupiter is bright – and in a telescope – quite large. As these horizon lines rotate,  Saturn sets, followed by Mercury and  then several hours later Pluto and eventually Jupiter. Meanwhile, Uranus rises in the east, followed in the morning hours by Mars and Venus.  Notice also that Pluto is just a tad beyond Neptune these days, though the distance between them will slowly increase.  The chart does show, however, that for a while Neptune was our most distant planet. See how Pluto’s orbit was inside that of Neptune? Don’t forget, Pluto takes 248 earth years to get around the Sun once. These events hold generally true no matter where you are in the world, but they need to be fine tuned for your latitude. Folks in the southern hemisphere, for example, get a much better view of Saturn and Mercury early in the month, than those in the north.

Finding Uranus

Uranus can be found with binoculars – or in exceptional conditions the naked eye – but locating it is an advanced project for those already comfortable with finding the naked eye bright stars and asterisms. You need full darkness, your eyes should be dark adapted, and you should be in an area where light pollution isn’t a serious problem.  That said, finding this planet is relatively easy if you have a decent pair of binoculars and patience.  Here’s a chart to use. After reading the directions below, click on the chart to get a larger version.

This Uranus finder chart is meant to be used firstw ith the naked eye, then binoculars. The red circle represents the typical view with wide field 7X or 8X binoculars. See text for instructions. Click on chart for larger view.

This Uranus finder chart is for September, 2009, about two hours after sunset. It is meant to be used first with the naked eye, then binoculars. The red circle represents the typical view with wide field 7X or 8X binoculars. Included on this chart are many faint stars that can be seen only with binoculars. See text for instructions. Click on chart for larger view. (Made from Starry Nights Pro with modifications.)

Start your search by locating Jupiter and the Great Square. You may also see Fomalhaut, a first magnitude guidepost star that will be introduced in October.

Next look below the Great Square for the “Circlet.” This is a well-known asterism in the constellation Pisces – but in typical suburban skies it is a difficult object and you may be able to pick out just three of the brightest stars in it with your naked eye. In rural skies you should be able to see most of these stars with the naked eye, but try to locate them with binoculars. The entire Circlet probably will not fit in a single binocular field of view, but enough of it should so you know what you are seeing.

Now use your binoculars to try to locate the trapezoid of fainter stars below the Circlet. This little unnamed trapezoid will probably fit in your binocular field of view. The faintest star of these four is just a bit brighter than Uranus, so that gives you an idea of what you seek.

Finally, with your binoculars scan up and to the right (west)  of this trapezoid and you should pick up an arc of three stars all about the same brightness. The third – the highest – of these is Uranus. While you won’t see a disc, you may notice that it shines with a steadier light than the other two. This is typical of planets. In a good telescope Uranus will show a tiny disc and perhaps a greenish tinge, but to the casual observe may be easily mistaken for a star.

Finding Neptune

Neptune is both easier and harder to find than Uranus. Again, binoculars and a dark sky are needed. What makes it easier is it’s near Jupiter. What makes it harder, is it’s signifcantly fainter than Uranus – so faint that whether you see it or not will depend on how dark your skies are.  You will need this little finder chart, however, to pick it out of the starry background.

Finding Neptune requires binoculars, or a small telescope, and patience. Fortunately, Jupiter drops us right in the neighborhood! See text for complete directions - and click on chart to get an elarged version. (Made with screen shot from Starry Nights Pro. I added names and arrow.)

Finding Neptune requires binoculars, or a small telescope, and patience. Fortunately, Jupiter drops us right in the neighborhood! See text for complete directions - and click on chart to get an enlarged version. This charts is for mid-September, 2009, about two hours after sunset. Neptune will appear to move slightly towards Jupiter during the course of the month. (Made with screen shot from Starry Nights Pro. I added names and arrow.)

Step 1 – find Jupiter, the brightest “star” in the eastern sky. The red circle represents a widefield binocular view. Your binoculars may show a smaller field. Also see if you can spot the two bright stars in our chart that are to the left – east – of Jupiter. They are bright enough so you should be able to see them even in typical suburban skies. In any case, you certainly should be able to find them with binoculars by first locating Jupiter, then scanning to the left – eastward.

Step 2 – after locating the two bright stars, use binoculars to look for the arc of three dimmer stars above them. These three are about the same brightness as Uranus and just at the edge of naked eye visibility under excellent, dark skies. For most people this means they will be seen only in binoculars. Neptune is to their left – east – as indicated.

And for early risers – Venus and Mars!

A crescent moon and Venus dominate the morning sky in the east, along with Mars and half a dozen bright "winter" guidepost stars. Click chart for larger image. SLightly modified screen shot from Starry Nights Pro.

A crescent moon and Venus dominate the morning sky in the east, along with Mars and half a dozen bright "winter" guidepost stars. Click chart for larger image. SLightly modified screen shot from Starry Nights Pro.

Don’t miss the autumnal equinox!

OK – if you’re in the southern hemisphere, this marks the start of spring. In the northern hemisphere, it’s autumn. In either case, it’s when the Sun crosses the celestial equator and day and night are almost of equal length.

The autumnal equinox this year is on September 22, 2009, at  21:28 Universal Time.

So what? Well, if you’re just starting out in star gazing, this is a great time to get your bearings at your observing site. That is, on or about September 22 – a few days either way won’t matter much – note where the Sun either rises or sets. That marks the due east – or due west – point on your horizon and from that you can easily figure out where north and south are.

It’s also the day on which the reading of your equatorial sundial switches from one plate to the other. That is, in the north you go from the north-facing dial plate to the south-facing (underneath) one.  See our equatorial wrist dial project. if you want to know more about this.

And finally, I find it cool that day and night are nearly of equal length. For one thing, that means the stars get a break. For the next six months here in the north we’ll have longer nights and thus more time to enjoy the night sky.

August 2009 – and all the planets have shown up for the party!

That’s the good news – the bad news is the “party” is an all-nighter. That is, if you really want too see all the planets – and maybe little, demoted Pluto as well – you need to start at dusk and stay at your task well into the wee hours of morning.  For Pluto, you will also need a powerful telescope and better charts than I’ll provide here, but the others can all be seen with the naked eye or binoculars.

But what I like about this situation is it makes it easy – even for those of us using nothing but the naked eye, which is really the focus of this web site  – to  see most planets on a single night and to get a sense of how their position in the sky relates to our position in the solar system and where we all are on our annual journey around  the Sun.

Astronomy is always about two realities – the reality we see and the reality we know. The trick is learning to merge these two so that when you see something in the night sky, you are familiar enough with what is really going on that what you see makes perfect sense, given what you know.


The best example of this is provided by the two major planets this month – Jupiter and Saturn. The chart above shows the reality we know. It shows where all the planets are at the start of August if you could get  above the plane of the solar system and look down at them. Study it. This is from the online orrery at “Solar System Live.” (http://www.fourmilab.ch/solar/)  I drew the bar across it to represents our horizon – the line between night and day –  and the arrows show the direction the bar is moving as night progresses. To the left this shows how, from our perspective, things are setting in the west – and to the right, how they are rising in the east.

Notice that in this view Saturn is near our western horizon and Jupiter near the eastern horizon. That’s the situation right around sunset. But the sky is too bright then for us to see even bright planets. We have to wait about 45 minutes. At that point, Saturn will look like a first magnitude star about 12 degrees above the horizon almost due west – azimuth 266 degrees – in the early part of the month.

Switch to the east and Jupiter is not so shy. It is at magnitude -2.8 (nothing gets brighter than this except Venus, the Moon, and the Sun), but it is still hugging the horizon. Chances are it is too close for you to see. Give it another 45 minutes – 90 minutes after sunset – and it will be about nine degrees above the horizon a bit south of east. For my latitude – 42 degrees north – it will be at azimuth 118. But the exact position isn’t too critical, since it is so bright and there’s nothing in that general vicinity at this time that will compete with it.

This will change slowly as the month goes on – that is, Saturn gets closer to the horizon at sunset each night and Jupiter rises earlier, until on August 14th Jupiter is rising in the east as the Sun is setting in the west.

Did you notice on the solar system view that Mercury is right over there near the western horizon as well? It is, but this happens to be a fairly poor showing for what is always an elusive planet to catch. Sky and Telescope gives this instruction: “Observers near 40° north can look for it 5° above the western horizon a half hour after sunset from August 6 to August 18th.” Yep – and it will be near magnitude “0” – but you will need a very clear western horizon to see it, and I suggest you search for it with binoculars.  Earlier in the month is better than later for both Saturn and Mercury. As the month goes on Saturn not only gets  closer to the horizon, but also closer to Mercury – and this will make  both very difficult to see. By August 17 the two planets are just 3 degrees apart, but then Mercury is only 2 degrees above the horizon and Saturn about 6.

Much easier to find are our two morning planets, Venus and Mars. Both can be spotted, without strain, with the naked eye. But Venus is by far the easiest. It is a brilliant  magnitude -4 – brighter even than Jupiter, which by this time is well over in the southwest, and should be easy to see low in the east northeast by 3:30 am. By the end of the month you’ll have to wait until about 4:30 am for it to be easily seen – but that’s still two and half hours ahead of sunrise.

Mars is a bit more of a problem, though it rises well ahead of Venus. At 3 am August 1 it is a first magnitude “star” about 7 degrees to the north of Aldebaran, also first magnitude,  and both are roughly 15 degrees above the horizon, a bit north of east. Because Aldebaran is a very red star, it will be interesting to compare it with the “red” planet, but it’s best to wait another hour to do this so both are higher in the sky and not as affected by the atmosphere, which tends to make every bright object colorful.

By the end of the month Mars is higher at 3 am, but Aldebaran is higher still. Mars will form an interesting triangle, though, with Aldebaran and another very red star, Betelgeuse. In fact, if you are up at that hour you get a preview of the early winter sky with the bright constellations of Auriga, Taurus, Gemni, and Orion coming into view, and Mars in the middle of them as our chart shows.

Mars early in th emorning at the end of themonth. Click for larger version. (This chart uses a screen shot from Starry Nights software which I have then annotated.)

Mars early in th emorning at the end of themonth. Click for larger version. (This chart uses a screen shot from Starry Nights software which I have then annotated.)

Returning to the evening sky, this remains a good year to track down Neptune and Uranus with binoculars. Both are relatively easy to find, but offer special challenges.

Notice on the solar system chart how Neptune is roughly in line with Jupiter as we view both from Earth. On August first a careful study of the Jupiter region with binoculars around 10 pm will reveal Neptune at about magnitude 8 and only two degrees to the north (left) – but finding it can be tricky.  Try putting Jupiter in the right-hand edge of your field – or even move your binoculars so Jupiter just drops out of the right hand edge. That way the glare from it won’t interfere with your view.  At that point Neptune should be pretty close to the center of your field of view. There are several stars nearby and both Neptune and Jupiter are changing position as the month goes on. Here’s a chart for August 1.

Neptune and Jupiter at the first of August, 2009. (Clickfor larger view.) (This chart uses a screen shot from Starry Nights software which I have then annotated.)

Neptune and Jupiter at the first of August, 2009. (Clickfor larger view.) (This chart uses a screen shot from Starry Nights software which I have then annotated.)

By the middle of the month, they have drifted a bit farther apart, and there’s a row of sixth magnitude stars in a gentle arc between them. If you compare the first chart and this second one you will see these stars and how the position of the planets change relative to them.

Neptune and Jupiter near the middle of August, 2009. (This chart uses a screen shot from Starry Nights software which I have then annotated.)

Neptune and Jupiter near the middle of August, 2009. (This chart uses a screen shot from Starry Nights software which I have then annotated.)

By the end of the month these same stars are closer to Neptune and the gap between Neptune and Jupiter is almost five degrees. That means they both probably fit in the same binocular field, but just barely.

If you look at the horizon line on our solar system chart – especially the eastern one – and note the direction it is moving, then you can see how our view will change during the night. As Jupiter and Neptune get higher we eventually get to a point where Uranus comes into view, then, well after midnight, Mars and Venus put in an appearance.

Uranus is easier to see than Neptune because it’s significantly brighter – about magnitude 6.  We also get a special break this month, for Uranus will form a wide “double star” with 20 Piscium, a star that is just a tad brighter than the planet. But this makes it easy to identify.  Here’s my way to locate it. First, trace out a few asterism in the sky south of east. (The following chart is for 11 pm EDT, August 1, at 40° North – but should serve as a general guide for almost any location.)

This charts helps you locate thegeneral area inw hich to find Uranus. Click forlarger version. (This chart uses a screen shot from Starry Nights software which I have then annotated.)

This charts helps you locate thegeneral area inw hich to find Uranus. Click forlarger version. (This chart uses a screen shot from Starry Nights software which I have then annotated.)

Next, you want to zero in on the Circlet of Pisces and an unnamed trapezoid below it.

Tracking down Uranus with binoculars. (This chart uses a screen shot from Starry Nights software which I have then annotated.)

Tracking down Uranus with binoculars. (This chart uses a screen shot from Starry Nights software which I have then annotated.)

The Circlet will not fit quite in the typical binocular field of view. The trapezoid should fit and maybe Uranus at the same time – but the way I find Uranus is to find the trapezoid in my binoculars, then move up so that only its top two stars are visible in the bottom of my field of view. Now up and to the right are two almost identical stars – the higher one is Uranus. It is about half a degree above 20 Piscium, a star that is just a tad brighter, though you will be challenged to tell the difference.  (The charts show only those stars you can expect to see with your binoculars – but depending on the binoculars and conditions, you may not see all of these stars.) Uranus is on the brighter side of magnitude 6 and at this point, at least 10 degrees above the horizon. Waiting until later in the night – or later in the month, this will only get easier as Uranus will get higher.  But as the month goes on it will pull away a little from 20 Piscium. By August 30 they are a degree apart and instead of Uranus being directly above 20 Piscium, it will have moved above and to the right – westward.

And Pluto? I wouldn’t try to hunt it down even with my 15-inch telescope.  Although it is relatively high in the south once it gets really dark, it is much too faint to see in anything except large amateur scopes. And to make matters worse, it has lots of competition, for it is above the Teapot in the middle of the Milky Way, and at magnitude 14, just a faint, faint dot among many, many other faint dots. Better to spend your time exploring the Milky Way itself. See: August Guideposts: Asterisms guide you along the Milky Way.

This is the general area within which you can find Pluto this month. But theplanet is faint and buried with the faint stars of the Milky Way.  (This chart uses a screen shot from Starry Nights software.)

This is the general area within which you can find Pluto this month. But theplanet is faint and buried with the faint stars of the Milky Way. (This chart uses a screen shot from Starry Nights software.)

A dreamy, planet-filled, midsummer night!

The sky will be filled with planets about 45 minutes before daybreak - BUT, only Jupiter and Venus will be easy to spot witht he naked eye. You might spot Mars, but binoculars will help and they certainly are needed for the rest. Neptune will be right next to Jupiter looking like a faint star, Uranus will be brighter, but refer to the chart for it. Mercury? You'll need ideal conditions to see it and that slither of Moon.

The sky will be filled with planets about 45 minutes before daybreak on the morning of June 21 - BUT, only Jupiter and Venus will be easy to spot with the naked eye. You might spot Mars, but binoculars will help and they certainly are needed for the rest. Neptune will be right next to Jupiter looking like a faint star, Uranus will be brighter, but refer to the chart for it. Mercury? You'll need ideal conditions to see it and that slither of Moon. (Click for much larger view.) This an all other charts here are screen shots taken from Starry Nights Pro software and slightly modified for this use.

June 20-21, 2009 – Midsummer Night –  is the shortest night of the year, but it is chock full of planets – all of them! ( Yes, we had a similar opportunity in May, and that was great fun – but it gets a tad better in June and there’s something a bit magical about Midsummer Night!)

In the hours before midnight you can enjoy Saturn in the western sky and as it sets shortly after midnight,  you can enjoy Jupiter and Neptune rising in the East. Pluto is there as well, low in the west, but it is so faint you’ll need a large telescope and lots of patience to track it down. Uranus will be the next one up, rising about 1 am, but not becoming easy to see for another hour or two. By 3 am Mars and Venus will have broken the eastern horizon. I don’t know how easy it will be to spot Mars with the naked eye. It will be just one degree from brilliant Venus and although it will be first magnitude, that will still be five magnitudes dimmer than Venus! In binoculars, however, it should be easy.

The difficult catch will be Mercury. My best guess is about 45 minutes before local sunrise (about 4:25 am for me in Westport, MA) it may be high enough if there are no clouds on the eastern horizon and the sky may still be dark enough. The thinnest of crescent moons may be a guide, assuming you can see it! Mercury will be about six degrees below the Moon and to the right – close enough to fit with the Moon in a wide-field binocular view, though typical 10X50 binoculars will not fit the two in the same field. Still, at zero magnitude it will be bright. Both of these are north of east – Mercury at about azimuth 67° and the Moon at  about azimuth 62°.

Frankly, I’ll consider myself very lucky if I spot Mercury – and I probably won’t have the patience to hunt for Pluto. If the skies are clear enough to see it, there will be too many other things to catch my interest, particularly near the southern Milky Way. But it would be kind of fun to pull an all-nighter – especially since this is the shortest night of the year – and to see all of what are currently called “planets” on the same evening. So if the weather is cooperative, I’ll probably start observing about 11 pm EDT.  And I’ll do my observing at a favorite location near the ocean where I have a great view of the eastern horizon – in fact, all horizons!

The charts which follow provide a guide to finding Neptune and Uranus.

Finding Neptune is easy, as long as you remember that at magnitude 8 it is much fainter than 5th magnitude Mu Capricorni, or the moons of Jupiter, all of which will be visible in a small telescope, or good binoculars held steady.

Finding Neptune is easy, as long as you remember that at magnitude 8 it is much fainter than 5th magnitude Mu Capricorni, or even the four brightest moons of Jupiter, all of which will be visible in a small telescope, or good binoculars held steady. Jupiter itself is second only to Venus in brightness at magnitude -4.6 (Click for much larger view.)

Uranus is a challenge to find with binoculars, though at magnitude 6 it will appear reasonably bright. Theproblem is, it's in a section of the sky without bright, maked eye guide stars. I dentify thegeneral search region by looking at the large chart at the start of this post. Then use this chart and search for the rectangle of 5th magnitude stars. Find themand it's a short star-hop up to Uranus.

Uranus is a challenge to find with binoculars, though at magnitude 6 it will appear reasonably bright. The problem is, it's in a section of the sky without bright, naked-eye guide stars. It does fit on aline between Jupiter and Venus and is about 27 degrees from Jupiter on that line. Identify the general search region by looking at the large chart at the start of this post. Then use this chart and search for the rectangle of 5th magnitude stars. Find them and it's a short star-hop up to Uranus which will appear to be the twin of the star closest to it. (Click for a much larger image.)

Dawn patrol: 5 Planets and a crescent moon – this will be cool!

OK, I’m normally up at this hour so it’s a no brainer for me – I’m heading to the Allens Pond Bird Sanctuary parking lotwhere there’s a great view of the eastern horizon, preferably on the morning of May 21. That’s when I expect a wonder-full view of five planets and the waning crescent moon. I plan to be there at 3 am, but it should get especially interesting between 4 am and 4:30 am. Later than that? Well, we’ll be in a race with the dawn – everything will get higher, as dawn approaches, making it easier to see –  BUT – so will the Sun which rises that day at 5:19 am. So the sky will get lighter making things harder to see.  And, of course, there’s always the weather question – but in this case, all the players will be around right into early June in approximately the same positions, except, of course, the moon. So while I will aim for May 21, weather will determine the actual observing date.

All of this is local time and date for 41.5 north latitude and 71 west longitude. But a good guide for elsewhere in the world is to simply find out the time of local sunrise, then start looking 90 minutes  before that. All the action as viewed from the Northern Hemisphere is  between east and southeast and the territory will be nicely defined – and easily found – by bright Jupiter,  brilliant Venus, and the Moon. This makes it an excellent opportunity for folks not familiar witht he outer planets Neptune and Uranus to take alook for them.

The more difficult targets will be Mars and Uranus – Neptune, since it will be so close to Jupiter, should be relatively easy – though binoculars will be needed for Uranus and Neptune and, of course, a small telescope willmake it all more fun. Here’s a chart from Starry Nights software  for what I expect to see, given clear skies of course:

(click for larger chart)

(click for larger chart)

For me the key is to look at this chart – look at the sky – and then keep firmly in mind what is really going on – which is this:

(click to enlarge)

(click to enlarge)

To understand how this display relates to what we actually see in the sky, consider that the Earth is rotating counterclockwise, and all the planets are revolving around the Sun counterclockwise.

That means that as the Sun slips below your horizon on the May 20 Saturn will already be high in your western sky. It will set by 2:30 am. But at around 4 am on May 21 you will encounter Jupiter and Neptune first and they will be highest. (That’s what the first line projecting from Earth represents.) Then as you let your eye move towards the horizon – counterclockwise, towards the Sun – you encounter Uranus, Venus. and last, Mars – as shown by the other lines. Not shown is the Moon which will be in line between Venus and Mars.

This representation is modified slightly from Solar System Live.  While all the planets are roughly on the same plane, if their orbits are represented by a blue line it means they are above the plane of the Earth. If it is represented by a green line – as is the case with the five morning planets on May 21, it means they are below the plane of the Earth.

The most difficult planet to find is likely to be Uranus. If  we have exceptionally clear skies and you have exceptionally good eyes you may be able to see it with your naked eye – but for most people in most locations binoculars will be essential. Here’s a typical 7-degree binocular field showing Uranus and stars to magnitude 8 from Starry Nights software. The star 24 Piscium is the brightest in the field at magnitude 5 – the other named stars in the circle – and Uranus – are magnitude 6. Fortunately, the general position of this field is easy to see by drawing a line between Jupiter and Venus (see the first chart). As you move from Venus up towards Jupiter, count three binoculars fields along this line  – Uranus  should be in the third field. Notice that Uranus is the last “star” in an arc of four reaching upward from the bottom of the field – the forth one being just below the field if you put Uranus at dead center.

(click to enlarge)

(click to enlarge)

Neptune is much easier to find. See this posting for details on it.

This is a good event for naked eye and binocular users. Yes, a small telescope will help. Jupiter and Venus will be fun to see in a telescope. Neptune and Uranus are too small to show anything except a tiny disc and Mars is a long way from us showing a disc only one-eighth that of Jupiter, so no details will be visible there either.

Interesting note: A friend in Austrailia said he would look for this, so I made him a quick chart for how things would look at 6 am in Australia on May 21. Compare that chart (below) with the view we get (first chart on this post) in North America.  Note how high Fomalhaut is for them – not to mention Jupiter and Neptune – and, of course, they look to the northeast as we look to the southeast.

The view from Sydney, Australia on the morning of May 21. (Click for larger image.)

The view from Sydney, Australia on the morning of May 21. (Click for larger image.)

%d bloggers like this: