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    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.

Events, June 2014 – Bright Lights Along the Ecliptic this Month

This is a great month to become familiar with the ecliptic in our sky. The ecliptic is the plane of our solar system where you will always find the Sun, Moon, and Planets.

Finding it sounds simple – and it is if you pick your time and date. The problem is it changes constantly because the Earth is tilted on its axis and revolving around the Sun.  I should stress one more thing – the ecliptic is not the path you will see the Sun, Moon, and planets take across the sky in a given night – it is the path they will follow as they change position over days, weeks, and even years. How quickly an object follows this path depends on how close it is to us – the Moon makes it completely around the ecliptic each month, the Sun each year – but a distant planet, such as Saturn, takes about 30 years.

You can trace the portion of this path visible about an hour after sunset on a June night in 2014. For the chart below I chose June 13th simply to include a nearly full Moon in the picture. It will, of course, change position each night – but the planets will stick pretty close to these general spots all month. So go out an hour or so after sunset and start your search by looking to the northwest for brilliant Jupiter. It will be brighter than any star, or any of the other planets and only about 10 degrees above the horizon – ten degrees can be measured by holding your closed fist at arms length.

Jupiter thus achors the western end of the ecliptic. We’ll move eastward to trace out the rest of it.

Click on this chart to get a much larger version. (Prepared from Starry Nights Pro screen shot.)

Click on this chart to get a much larger version. (Prepared from Starry Nights Pro screen shot.)

 

Up above Jupiter are the famous Gemini Twins – the nearer and slightly brighter one is Pollux, the other is Castor.

Turn a bit south of west you will find the bright star Regulus. While it outshines most other stars visible tonight, it is just in between Castor and Pollux in brightness and is about 30 degrees above the horizon – three fists.

Next on our list is the red planet Mars – the second brightest object on our chart. If you’re not detecting the rusty redness of it, try looking at it in binoculars. Then compare it with the next bright star on our chart, Spica. Spica is a  little lower than Mars an quite a bit dimmer. (Mats is four fist high, Spica about three and half.) Spica, however, is a very hot – and thus very blue – star. Look at the difference in color between it and Mars.

Moving eastward you’ll find Saturn, whose beautiful rings will show in even a small telescope. However, to the naked eye and binoculars Saturn simply looks like a bright star – not as bright as Mars, but certainly brighter than Spica. It has a pale, yellowish hue.

Continuing to the east is Antares, just 15-degrees – a fist and a half – above the horizon.  It’s name means “rival to Mars” and for good reason – it is a classic, red star, rivaling the color of Mars.  Again, contrast its color with that of Spica and Mars.

Oh – high overhead is the bright star Arcturus. It’s about as bright as Saturn and nearly 70 degrees above the horizon – seven fists.  Do you remember how to find Arcturus? You “follow the arc” of the Big Dipper’s handle – now high in our northern sky, to Arcturus, then “drive a spike” to Spica.

What else is going on this month?

Well, two dates to keep in mind:

The Summer Solstice is June 21 at 6:57 am EDT – and thus begins the longest day of the year.

On June 24 a thin crescent Moon will be very close to the brightest of planets, Venus in the eastern sky about an hour before sunrise. Should be a pretty sight and a nice picture opportunity.

February 2014 Events: Obvious Jupiter, Morning Venus, Subtle Zodiacal and a timely wink from the Demon

Yep, you can’t miss Jupiter this month.  It’s well up in the eastern sky as it gets dark and brighter, by far, than even Sirius, the brightest star we folks in the north see.

What other special events are on parade this month? Well, the Moon provides a wonderful viewing – or photo op -with Venus in the predawn sky late in the month; the last two weeks of February will be a good time to look for that elusive Zodiacal Light about 80 minutes after Sunset, and if the weather on February 17 cooperates, we have a perfectly timed eclipse of Algol, the Demon Star, for folks in the Eastern Half of the US. ( There are other dates with the Demon available too for other parts of the world.)

So let’s start with Jupiter. You really can’t miss it even if you’re a beginner. In fact, if you’re a beginner this is a good time to let Jupiter be your guide to the Winter Hexagon. As mentioned in our “look east” post, you’ll find it in Gemini. Look to the southeast a couple of hours after sunset and here’s what you should see.

Click image for much larger version. To get the full beauty of this section of sky find an area with a clear horizon to the southeast and go out on a February evening a couple of hours after sunset. The chart shows what you'll see. The link below provides a small black-on-white version you can print and take into the field. (Prepared from a Stellarium screen shot.)

Click image for much larger version. To get the full beauty of this section of sky find an area with a clear horizon to the southeast and go out on a February evening a couple of hours after sunset. The chart shows what you’ll see. The link below provides a small black-on-white version you can print and take into the field. (Prepared from a Stellarium screen shot.)

Click here for a printable map of the above chart.

Jupiter reaches its highest point as it crosses to the south about 5 hours after sunset near the start of the month and closer to three hours after sunset at the end of the month. As the chart shows, Sirius will be lower and more to the south.

Moon and Venus team up for a Picture Perfect  Pre-dawn Sight

Venus is a morning star and really stays pretty close to the Sun this month, but as Sky and Telescope points out, there’s a great meeting of Venus and a thin crescent Moon on the morning of February 26. Here’s what to look for then.

Click picture for larger version.

Circle shows the typical view through ordinary binoculars – you may just be able to fit them both in the same field of view. Click picture for larger version.

Soft, elusive, and fascinating – Zodiacal Light

Mornings not your thing? Well from February 16 to March 2 the Moon will stay out of your way if you go out about 80 minutes after sunset and look for the elusive, zodiacal light. This is faint – sort of like the Milky Way – but its a pyramid of light rising up from where the Sun sets and going roughly halfway up the sky and leaning to the south.  To see it you must have dark skies pretty much free of light pollution. (A city to your west, for example, would likely ruin it.) And, of course, your eyes must be dark adapted.

Still, it’s a fascinating cloud of fine dust. Here’s what I said about it a couple of years ago – and it still applies:

You don’t need a totally clear horizon to see the zodiacal light, or binoculars, but you do need total darkness and that means little-to-no light pollution and no Moon. So you want to wait until a few days after full Moon to begin this quest. I feel I have a good shot at it from my favorite ocean-front observing point where I have a clear horizon to the west with no cities to create light domes there. Evenings in February and March – and mornings in September and October – are the best time for folks at mid-northern latitudes to look for this.

The zodiacal light is roughly the same intensity as the Milky Way, so if you can see the Milky Way from your chosen location, then you should be able to pick up this faint glow. Like the Milky Way, it stretches over a good deal of sky. It is widest near the horizon and gets narrower as it rises towards the zenith. You want to look for this starting  roughly 80 minutes after sunset. You can check for an exact time for your location by getting information from here on when astronomical twilight ends. (The drop-down menu on that page specifies the times for astronomical twilight.) As astronomical twilight ends you want to start looking. As with any faint object, your eyes need to be dark adapted, so I am assuming you have been out for at least 15 minutes with no white light to dazzle you. If you try to look for this earlier, you may confuse it with twilight. Much later and it is not as bright, for what we are seeing is sunlight reflecting off interplanetary dust particles – dust particles that orbit in the same plane as the planets – the area we call the zodiac – and thus the name for this phenomena, zodiacal light.

If you see it, reflect on this explanation from Wikipedia:

The material producing the zodiacal light is located in a lens-shaped volume of space centered on the Sun and extending well out beyond the orbit of Earth. This material is known as the interplanetary dust cloud. Since most of the material is located near the plane of the Solar System, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is amazingly small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth’s Moon, each particle would be 8 km from its neighbors.

For the metrically challenged (that includes me), that means one dust particle every five miles! And that causes all that light?! Awesome!

Now, about that Demon!

I wrote about Algol the “Demon Star” in this  posting for October, but it’ s still well placed for viewing in February, and if you look at the right time, you’ll catch it in mid-eclipse, which is cool. For those on the East Coast, the most convenient time will be roughly 7:45 pm. Technically, the eclipse goes on for about two hours with the lowest point – the star at its dimmest – at 8:44 pm EST.  But to appreciate this you should check it an hour before to see the normal brightness, then look again at 8:44 pm. Of course, you could start at 8:44 pm and note how it brightens during the next hours. Either way, it will convey why ancient star gazers considered this the “Demon Star.” These events happen often enough for them to notice it dimming every once in a while – sort of winking at them – and no other bright star does that, so it’s easy to imagine the stories that would be told.

Every 2.3 days Algol dims like clockwork, but it is only at its dimmest for about two hours, so to see it in this condition you really need to be watching at the right two hours. Fortunately, there are several places that will give you a list of times when this occurs – but many of these times will be while normal people are sleeping – and many more will be during daylight hours. However, each month there should be one or two dates when it is really a good time for you to catch Algol doing its thing.

Most of the listings I know of for Algol “minima” give date and time in Universal Time. What I like about the one at Sky and Telescope magazine, is it will calculate a list of coming Algol minima for you – and give you the Universal Time, plus your local time. So it’s easy to glance over it and see when it will be most convenient – weather permitting – for you to take a look. In my case, February 2014 gives me a couple of opportunities worth noting:

  • 02/14/2014 @ 11:55 pm
  • 02/17/2014 @ 08:44 pm

With winter weather it’s easy to get clouded out, so the more opportunities the better your chance of seeing something. I find these eclipses amazingly elusive and rarely see one, maybe because I think there’s always going to be another opportunity – and there will, but . . .

December Events – a brilliant crescent Venus, Jupiter, and moon-drenched meteors

Venus – brilliant shortly after sunset to southwest

Chart shows position of Venus, roughly two fists (18 degrees) above the southwest horizon for much of December. During the last half of the month it will move closer to the Sun - and thus closer to the horizon half an hour after Sunset and by the end of the month will only be about 8 degrees high.  Vega and Altair will be much dimmer, but should show within about 45 minutes after sunset. (Created from Starry Nights Pro screen shot.)

Chart shows position of Venus, roughly two fists (18 degrees) above the southwest horizon, for much of December. During the last half of the month it will move closer to the Sun – and thus closer to the horizon half an hour after sunset and by the end of the month will only be about 8 degrees high. Vega and Altair will be much dimmer, but should show within about 45 minutes after sunset. (Created from Starry Nights Pro screen shot.)

For telescope users – and maybe even those with binoculars – Venus does a gorgeous job of showing off its phases this month as it shrinks and grows at the same time.  For all of us, with telescope or not, it’s a brilliant “evening star” dominating the southwestern sky about half an hour after sunset.

Galileo was the first to see this and it was part of his argument for a Sun-centered solar system. Like Galileo, if you really want to see the phases you need a telescope, though near the end of the month you may be able to detect its thin crescent with good binoculars held very steady.

You won’t have any trouble finding it.  It’s that most brilliant “star” about 18 degrees – a little less than  two fists held at arm’s length – above the southwestern horizon half an hour after sunset.  It shrinks in terms of the amount of its disc that is lit. At the start of December 2013 about one third of the disc is lit – by the end of the month this will drop to just 5 percent. Amazingly, it stays almost the same brightness all month – in fact, this is the time it is at its most brilliant. Why? Because it is overtaking Earth in its orbit and in January will pass between us and the Sun – a sort of “new moon” phase, then become visible in the morning sky. ( When Venus is in its “full moon” phase it is farthest from us, so even though nearly the entire disc is lit, it does not appear nearly as bright.)

Positions of inner planets in mid-December, 2013. All are moving counter clockwise and Venus is about to overtake the Earth, passing between us and the Sun.

Positions of inner planets in mid-December, 2013. All are moving counter clockwise and Venus is about to overtake the Earth, passing between us and the Sun. Mars is positioned to be seen in our morning sky and Mercury is visible at the start of the month before dawn, but is pretty much lost most of the month in the glare of the Sun.

And about the growing Venus? Well, as it gets nearer to us it also appears larger. At the start of the month it’s disc about 38 seconds in diameter – by  the end of the month it is nearly a full minute of arc in diameter. To give you an idea what a minute of arc is, stand on the goal line of a football field and have a friend go down to the 10 yard line at the othe end and hold up a quarter? Can you see it? You may be able to if you have excellent vision.

On the other hand, a quarter held nine feet away is roughly the size of the full Moon – or Sun – in our sky – about 30 minutes of arc, or 30 times larger than Venus will appear in a telescope at the end of the month.

If you do go looking for the Venus crescent with binoculars or a small telescope, go out early. Locate  it while still in twilight, about half an hour after sunset. There’s less glare then and so it is easier to see the form. Later, as it gets fully dark, Venus is so bright you may find detecting its crescent difficult even in a telescope.

Jupiter – very bright as it rises in the east a couple hours after sunset

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

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

So is Venus the only special show in in our December skies this year? No. If you wait until “prime time” – about 8 pm – you will see a very bright “star” rising in the east. This is Jupiter, which by the end of the month starts coming up right after sunset.  Once it’s fairly high in the sky it makes a good target for binoculars. Its disc won’t be quite as large as Venus, but it does have four bright Moons and you can almost always find one or two of them with binoculars – sometimes three or even four.  Galileo did it four hundred years ago with a telescope that certainly wasn’t as good as most modern binoculars, but was a bit more powerful. Again, you need to hold your binoculars steady and focus them carefully.

Geminids – nice, but they will be drowned out some by moonlight

We also have the best meteor shower of the year putting in its annual appearance in December – the Geminids. Unfortunaetly, this year it will have to compete with the nearly full Moon. Still, Geminid meteors tend to be slow and quite bright, so even with the Moon you should see some. The shower is forecast to peak just after midnight (EDT) on Saturday morning, December 14th. That means late on the night of December 13th – hmmm, Friday, the thirteenth – should be good for seeing Geminids and the best views  will come in the very early morning hours of Saturday when the Moon is low in the west and the shower’s radiant point – in Gemini near Jupiter – is high in the sky.

Solstice – December 21, a good reason to celebrate

You need not be a Druid to celebrate this just after midnight EDT on December 21, 2013.  For northern hemisphere observers the winter solstice means the Sun has stopped running south and is turning around and heading back north. Of course it will take a few months before it’s warming rays change our weather much, but the fact that it is heading back north is a good sign.

It’s hard to imagine just how much that would mean to people living off the land and dependent on the seasons. Even in my warm home I am  cheered by the change, Every morning when I take the dogs out I see the Sun rising on the southeast horizon. At this time of year it appears to stand still for a week or so – but by the end of the month the northward movement becomes noticeable as I mark its path by the trunks of the bare trees I see it through. Of course for those of you in the southern hemisphere this marks the start of summer.

Christmas Star – it’s in your heart, but either Venus or Jupiter will be a nice reminder

In December I frequently get asked about the Christmas Star and while competing scientific theories have abounded about it for centuries, in the final analysis it is a Christmas myth that you can choose to believe, or not believe. Various scientific explanations – informed guesses – range from certain gatherings of planets, to a comet or super nova. Part of the problem is we don’t know the date – not even the year – Jesus of Nazareth was born, so various astronomical  – and astrological – possibilities exist depending on the date chosen. Me, I just take any bright star that’s visible and treat it as  a symbolic Christmas Star. This year we have Venus in the west for a couple hours after sunset – and by the time it sets we have a very bright Jupiter rising in the east.

Solar eclipse , Comet ISON, Venus, Jupiter, Saturn, Mars . . . welcome to November, 2013

COMET ISON UPDATE – NOV  30

 ISON bottom line: Awesome new movies from STERO spacecraft you can see right now – but prospects for naked eye observation very dim – though we’re still talking about a comet and as one scientists said recently – comets are like cats – they have tails and they do what they want.

Best web site I’ve found so far is this NASA blog. Scroll to the movies and the text below that explains them well. This is a rare view of a sun-grazing comet. 

As you look at the images of ISON keep a couple things in mind – first, the Sun is huge – you can fit 109 Earth’s across it’s face – so judge the changing size of the comet by that. Second, ISON is coming from the outer reaches of the Solar System where it is made of the same material from which the Earth and other planets were formed 5 billion years ago – material in its relatively pristine state. That’s one of the things that excites the scientists. Think of it as a space probe in reverse – a probe that not only goes to the outer reach of our neighborhood, but in a real sense goes back in time billions of years.

Of course, the main question has been what will ISON look like after this close-encounter with the Sun and the best answer right now is that it will be a good target for experienced astro imagers with the proper equipment – but it is very doubtful that it will be visible to the naked eye. I’ve updating this page in the hopes that we would be able to observe Comet witht he naked eye  some cool December morning – but it now looks like that will not be the case. But with these special movies it still has proven to be a mind-blowing, visual treat and no one has to get cold or lose sleep to enjoy them. 😉

COMET ISON UPDATE – NOV  19

Got my first look at Comet ISON this morning – sadly, not impressive.

It, of course, may still burst into full glory after it rounds the Sun on Thanksgiving – or it may break up, or it may just be so-so – have to wait and see.

At about 5:35 am when I was looking with 15X70 binoculars it was easy to spot as I scaned between the bright star Spica and even brighter Mercury which was low down, well in the morning twilight. ISON was roughly halfway  between – well, closer to Spica.

Also, a near full moon was still 26 degrees up in the west and washing out all but the brightest stars. Between morning twilight and the Moon these are pretty terrible conditions to see any comet. ISON appeared to me as nothing but a fuzzy star about 13 degrees (little more than one fist) above the southeastern horizon. Here’s a chart –http://observing.skyhound.com/ISON.html

COMET ISON UPDATE – NOV  16

Comet ISON is brightening and the Messenger spacecraft orbiting Mercury is about to get up close and personal not only with ISON, but with a second comet as well -very, very unusual.

Comet ISON is undergoing a sudden brightening – so there’s hope at last that even if we get clouded out now it might put on a good show right after Thanksgiving. And the Mercury flyby more exciting news from a science standpoint.

Right now ISON is in the pre-dawn sky and on the edge of naked eye visibility -and, of course, we have clouds in the forecast! However, the clouds will not impact the view from Mercury where we have a spacecraft circling that planet that can be used to examine not one – but two comets that will fly close by the planet in just a few days.

This is an incredible coincidence – comets can approach the Sun from any angle or direction and the chance that they pass especially close to any given planet are slim – that two comets should pass very close to Mercury in just two days. . . well, read all about it here:

http://science.nasa.gov/science-news/science-at-nasa/2013/15nov_twocomets/

I still don’t expect a whole lot from ISON in the next week, but who knows. Seeing it will require getting up early and, of course, very clear skies.

To learn more details about ISON go here  and to follow the latest reports, go here.

COMET ISON UPDATE – NOV  5

COMET ISON is still a fairly faint object visible in large astronomical binoculars and small telescopes in the morning sky – where there are currently three other small comets that are brighter – at this time – than COMET ISON and one of these may become visible to the Naked eye in the next week or two.

I really like the following summary from an excellent comet web site found here.

“How can ISON still be a Great Comet? ISON is running considerably fainter than initially hoped, and this trend has continued into November. But just as there is a chance that it will disintegrate one night, ISON could also flare up, becoming much brighter. In December a long tail may be visible on the pre-dawn horizon, regardless of if it survives or not. This tail could be spectacular to the eye, but even if it isn’t, it could still be spectacular in photographs.  We have no way of knowing, and this is what makes observing comets so much fun. Hang on, get out there as often as you can to have a look, and enjoy the ride!”

To get details on the other three comets – including detailed finder charts, go here.

—————————————————————————–

With an unusual solar eclipse, perhaps a major comet, and planets galore – November 2013 should be an exciting month for those who look up!

The partial solar eclipse is this Sunday (November 3, 2013) and for those on the East Coast is underway at Sunrise. Also it is better the farther north you are.  But this is really the tail end of an unusual eclipse event, much of which takes place over the Atlantic Ocean. PLEASE KEEP IN MIND THAT WATCHING THIS EVENT REQUIRES SPECIAL PROTECTION FOR YOUR EYES! For details on what you will see from where and when you will see it, go here.

The “maybe major” comet is Comet ISON, of course, which we have been hearing about all year. It’s already well within the range of amateur telescopes and it may brighten enough to be seen with binoculars, or even the naked eye before the month is out – but the best view will probably come the first couple weeks of December.  In all cases this is a morning sky event. No one can give any guarantees on a comet – it may be spectacular, it may be a dud – I think it will likely be somewhere between these extremes. But it is coming close enough to the Sun to break up and if that happens too early in its encounter,  it will be a total dud – happen later and it could make it all the more spectacular – and, of course, the break up might not happen at all.

Comet ISON is in the morning sky now and as it draws near the Sun it will get brighter – but it also will be seen against a sky background that grows lighter because of dawn. This is part of the tension comets usually create – they’re at their best when they’re closest to the Sun, but the closer they get to the Sun the  more into twilight skies they appear.  To learn more details about ISON go here  and to follow the latest reports, go here.

A really easy – and predictable – show no one can miss right now is  that brilliant “star” low in the southwest about half an hour after sunset.  It’s no star, of course, it’s the planet Venus – and it has been hanging around low in the western sky much of the year. But in November it draws closer to Earth as Venus starts to overtake us in our orbit.  This means that through a small telescope you can watch it change form into a miniature crescent moon shape. But while it shows us less surface area as it starts to pass between us and the Sun , it gets brighter because during this time it is also getting closer to us. It gets a little higher as the month goes on and by the end is nearly two fists above the southwestern horizon about half an hour after Sunset.

Meanwhile, over in the eastern sky Jupiter is starting to put on a show at a reasonable hour. It has been with us for months now, but visible only to early risers. In November it brightens and it rises high enough, early enough, for many to see it before going to bed. At the start of the month it is rising at about 10 pm, but then we switch to  Standard Time and it rises at 9 pm. By the end of the month rise time is about 7 pm. At about magnitude 2.5 it is brighter than any star, but can’t hold a candle to Venus.

So near the end of the month and early December a dazzling Venus will be well above the horizon to the south west – then as Venus sets, Jupiter  will be rising to the east. Nice show – though you will probably have to wait another  hour for Jupiter to be easy to see.

Meanwhile, in the morning sky this month we have ISON growing brighter and coming near some familiar objects – the bright star Spica and the planets Mercury and Saturn. From what I’ve read to date I think it’s reasonable to assume it will be a nice binocular object this month and possibly reach naked eye visibility. Key dates put it reasonably close to Spica around November 16 and  Mercury and Saturn  about November 22. But again, I suggest you look at the charts and follow the updates here.  Another place to look for reporst from amateur astronomers following Ison is the the discussion thread on Cloudy Nights found here.

August 2013 – last good look at Saturn, and a Moon-free Perseids shower

The Big Dipper's handle can guide you first to bright Arcturus, then to yellowish Saturn and blue Spica - both will be about the same brightness. Venus is much birghter, but best seen about half an hour after sunset when it is about 10 degrees above the western horizon. By an hour after sunset it ishalf that or less and even if you have an unobstructed horizon, may be lost in mist and twilight.

The Big Dipper’s handle can guide you first to bright Arcturus, then to yellowish Saturn and blue Spica – both will be about the same brightness. Venus is much brighter, but best seen about half an hour after sunset when it is about 10 degrees above the western horizon. By an hour after sunset it is half that or less and even if you have an unobstructed horizon, may be lost in mist and twilight. CLick for larger image. (Prepared from Starry Nights Pro screen shot.)

For a printer friendly version of the above chart, click here.

If you have a small telescope, August 2013 will give you your last good look at Saturn for the year and if you live on the right side of the globe – not where I live – the Perseids  meteor shower should be spectacular this year with no interference from a waning Moon.  Venus, meanwhile, continues to reign low in the western sky just after sunset.

The sky north of east early on the morning of August 12, prime time to watch for Perseids meteors. (Created froma Starry Nights Pro screenshot.

The sky north of east early on the morning of August 12, prime time to watch for Perseids meteors. (Created from a Starry Nights Pro screenshot.)

For a  printer friendly version of the above chart click here.

The Perseids should reach their peak on August 12 at about 19:00 UTC. To find what time that is for your region, go here.  For about half the world that’s good news, for the other half it’s bad because you really want to see this shower in the early morning hours and you will get the best show if the shower’s peak falls during those hours for your time zone.

Locally, on the East Coast of the United States, I’m going to watch the weather and if either the morning of August 11 or the morning of August 12 is forecast to be clear, I plan to start observing about 2 am. But I am not expecting a big Perseids show – just a nice summer night with a much better chance than usual of seeing a bright meteor.

Meanwhile, I’m bracing myself to hear a lot of promotional blather about the Perseids locally from TV weather folks and others who should know better, but the truth is in North America the timing of this year’s shower could hardly be worse.  The shower is best for a couple hours either side of its peak and its peak is forecast to come at 19 hours GMT on August 12 – for Eastern Daylight Time that translates to 3 pm – broad daylight.  What’s worse, even if the peak was in the early evening hours, the Perseid’s radiant point doesn’t get high in the sky until the early morning. That’s why the best time to see Perseid meteors – regardless of the peak time – is still  between midnight and  a couple hours before dawn.

So can we in America hope to see any Perseids at all? Yes, of course we can.  Just don’t expect a “shower.” In fact, I have to say that i always wince a little at the times and rates of meteors frequently given in news reports. Hey, just the word “shower” implies a lot more than most people usually see, especially from their typically light-polluted back yards.  When someone reports that the Perseids will peak at better than 100 meteors an hour, they usually fail to mention that three conditions have to be met for you to see that peak.

1. You need the Perseids radiant point to be nearly directly overhead – for EDT that occurs in a twilight sky, but is reasonably high from midnight on. The meteors may appear in any part of the sky, but they will appear to radiate from that point, so the higher it is, the better chance we have of seeing a meteor.

2. You need very dark skies – skies that will allow you to see magnitude 6.5 stars, if you are going to experience those real high rates. I have never experienced such dark skies, but they certainly exist. However,  with my reasonably dark skies I am very happy when I can detect a star of magnitude 5.

3. And, of course, you need the shower’s peak to coincide with the radiant point being very high in your sky.

One more caution – anything can happen. This is a forecast and usually reliable. But there could be a burst of meteors at a different time. You may get lucky.

And if all these  condition aren’t met for your location? Well, it’s reasonable to expect to see a Perseid meteor about every 10-15 minutes – of course you  may get two or three in a row hardly separated at all, then not see another one for  an hour. But be patient and you will get results – just not the meteor spectacular that some reports will imply. Last year they were coming in at a rate of 15-20 an hour four hours either side of the peak.

And yes, a Perseid can show up days either side of the peak.  How will you know it’s a Perseid? Draw a mental line extending the path of the meteor back towards the Perseid’s radiant point. If your line points back to that area of the sky – see map above – then you saw a Perseid. But there are always strays around – random meteors that have no connection to the shower – and at this time of year we have a couple weaker showers that may produce a few meteors going in other directions.

Meteors and meteor showers are fun if for no other reason than they are a chance to see something happening in the sky. Much of what we look at doesn’t change – or rather changes so slowly we don’t notice the change. Meteors, on the other hand, demand that you be looking in the right place at the right time. Only on the very rare, very bright meteors do we actually have time to alert others and have them turn their heads and see what we see.  And what we see is a space event happening closer to us than any other natural one. What’s more, meteors can have real scientific value.  They are viewed by some as our cheapest “space probe.” They are relatively pristine bits of matter left over from the early days of the solar system and so can tell a story to those who know how to read them.

Meteors – “falling stars ” – can be seen any time. You don’t have to wait for a “shower” like the Perseids; you just have to be lucky. But they are most frequent at certain times in the year when the Earth happens to be plowing through a meteoroid-rich area.  We call this occasion a meteor shower. (For your dictionary: A meteoroid is a small bit of space rock that becomes a meteor when it collides with our  atmosphere and heats to incandescence as it descends towards Earth. When it gets here – which is rarely as anything except fine, incinerated dust – it is a meteorite. )

The reason for a shower such as the Perseids is that we are passing through the debris trail of a comet. Think about it. The general model for a comet is a “dirty snowball,” and as that dirty snowball nears the Sun it melts, and as it melts it leaves a trail of dirt particles behind it – particles that remain in orbit until something like the Earth sweeps by and captures some of them with its gravity.

The comet itself can vanish entirely – but the result is a river of space dust – a river that is most intense nearest where the comet actually was.  That’s why there are some years – the 1990s in the case of the Perseids – when the meteor shower is more intense than others.  Now we are in a period when we are passing through the trail of the comet that creates the Perseids at a point where that trail is relatively sparse – so there will simply be fewer Perseids than there were  15-20 years ago.

That trail is not encountered all over the sky. It collides with our atmosphere near a particular point in our sky. That point is called the radiant – you might think of it as a hole through which the Perseids fall – and in the case of the Perseids, it appears to be in the constellation Perseus.  But we don’t see all the meteors at this point. We see a meteor only when its collision with our atmosphere is intense enough to make it burn up. The faint meteors we see are made by a speck of dirt about the diameter of a pencil lead. The brightest ones are caused by something about the diameter of the pencil’s eraser.  In either case it will, for all practical purposes, burn up entirely in our atmosphere – 50 to 75 miles up – and nothing significant will remain for anyone to find on Earth. But exactly where it burns up is another thing. That’s why we will see a sudden flare – a falling star – anywhere in the sky.

And that’s awesome! Consider this: If someone struck a match 50 miles away would you see it?  Yet a grain of sand, hurtling into the atmosphere, shows us such a brilliant light we can’t miss it! Why? Well, for one thing it is hitting our atmosphere at something in the order of 133,000 miles an hour – that makes a “speeding bullet” look like the proverbial turtle!

When you are watching for Perseids, you don’t have to look near the radiant point, though you will see more there.  A meteor can flare up suddenly anywhere and appear to draw a short (usually 5-10 degrees long) straight line across the dome of the sky. (Bright ones may actually leave a trail, which you can see for a few seconds with the naked eye or longer with binoculars.) If we trace a line backwards along the meteor’s trail we will see it comes from the area near the radiant point.

In the early evening, that Perseid radiant point is low in the northeast. That means nearly half the meteors that are radiating from it are happening below our eastern horizon. That’s why the shower is best in the early morning hours when the radiant is high in our sky. If the radiant is overhead, then we have nearly doubled our chances of seeing a meteor.

There are many meteor showers in the course of a year and some are better than others. The Perseids is one of the most reliable ones and happens to come at a convenient time for northern hemisphere observers when it is comfortable to be out at night, lying on the ground, and looking up.

In the final analysis there’s only so much time you can spend lying on your back gazing at the starry sky; though I very much enjoy that time, it’s made much more enjoyable by knowing that at any instant there’s a heightened likelihood that I will see a bright meteor.  That – and the summer Milky Way – make looking for Perseids in a dark and moonless sky always worth the effort for me.

Events December 2012: Mercury, Meteor Shower, Dwarf Planet, Jupiter, and more!

geminids

OK, so the meteor shower might be a snow shower, it being December and all, but we also get  an especially nice apparition of Mercury with Saturn and Venus guiding us to the elusive planet. And if that’s not enough, we have the ever reliable Winter Solstice – start beating the drums to bring the Sun back out way, please – and the King himself, Jupiter dominating an already brilliant eastern evening sky  plus a nice asteroid pass to accompany a not-quite-as-bright Dwarf Planet – you know, one of those Pluto-like things! Whew – out of breath just thinking about it all.

Here are the links to one  event at a time if you want to jump straight to the details.

Geminid Meteor Spectacular – December 13-14

First, please meditate on this: Ask someone who is 50 miles away to strike a wooden kitchen match. Can you see it? Of course not. But that’s what’s going on when you see a meteor flash across the sky! Chances are it is from a particle about the size of the head of a kitchen match – or smaller –  and it is burning up as it hits the atmosphere above you travelling at up to 100 times faster than a rifle bullet.The result? A very, very bright “match.”

And now the Geminids – As you may know, I really don’t like that word “shower.” It builds expectations out of proportion usually, but if you have clear skies on the night of December 13-14th it’s worth digging that folding  chaise lounge out of storage, wrapping yourself in a sleeping bag – with binoculars and hot beverage handy – and staring up at those wonderful bright stars of winter waiting for some to “fall.”  Hey, if you have an Iphone or Ipad there’s an app for this – no kidding – you can record what you see and ship it off to NASA, thus contributing to scientific research –  all quite painlessly. (Go here for details.)

Oh – and this is the time of new Moon, so the Moon won’t be present to upstage the show with its bright light. The official word goes something like this – expect “about 120 meteors visible per hour for an observer at a dark sky site late on the peak night.”  That’s how Sky and Telescope puts it and those folks certainly know what they’re talking about, but in many nights of meteor watching I’ve never seen anything close to 120 per hour. When that’s the forecast I figure I have a good chance of seeing 20-30 an hour and believe me, that’s a real treat.  Maybe your skies are darker than mine, maybe your eyes are better, and maybe you’re more patient – so maybe you’ll see 120. Me – I will be delighted with a meteor every two-to-three minutes –  if not a quite a shower, that’s a  snappy snow flurry!

So where do you want to look? Up! Any part of the sky  can produce meteors, but if you trace their trails backward you will see they all emerge from the same general section of sky near Castor, the slightly dimmer Gemini twin.  Since they appear to radiate from this area of sky the most meteors will be visible when it is high overhead – and looking in that general direction is a good idea. Here’s a chart for 1:46 am ET -when Castor is at its highest – on the morning of December 14.

Click image for larger version. (Prepared from Starry Nights Pro screen shot.)

Click image for larger version. (Prepared from Starry Nights Pro screen shot.)

So does that mean you have to wait until  early morning to enjoy the Geminids? No! But it makes sense that if the radian point is near the eastern horizon – which it is a couple hours after sunset – then you cut your chances of seeing a meteor in half – which still means a very respectable number of meteors.  The higher the radiant point the more chance you have of seeing more meteors. But then, you can’t watch the whole sky at once – even if you have remarkably clear horizons – and one thing about meteors – they are very fast and there’s no instant replay. Blink – or be looking the wrong way – and you may hear the ooohhs and aaaahhs of companions, but you will most likely not see what they saw.

Most meteor showers are the result of the Earth passing through a trail of comet dust  – think of “Pigpen” in “Peanuts” and you get the idea of comets leaving a trail of dust. But not the Geminids. They’re something of a mystery, but the current theory is that they come from a maverick asteroid. To read all about it, go here.

Hey – why not do the observing right?  Go out about 2 am and enjoy a couple hours of meteor watching, then shift your focus to the eastern horizon where Saturnn, Venus, and eventually Mercury will put in an appearance – quite a show, really.

Mercury – an early month, early morning stage appearance with Saturn and Venus

Mercury  reaches longest elongation – distance from the Sun –  on December 4th and while it will be well-placed for another couple weeks, you need to grab the little winged messenger when you can. It pops above the horizon six times a year – three in the morning sky and three in the evening sky, but not all pops are created equal. This happens to be its best appearance for 2012.  As a bonus, brilliant Venus will act as a guide. The two planets will be closest on December 9th when you should be able to squeeze them both into the same low-power binocular field of view. But all month they will be close enough for Venus to help in finding Mercury and Saturn will be visible a bit above Venus.

Of the three, Venus will absolutely dominate in brightness at magnitude -3.9. But Mercury on December 4th will be just a tad dimmer than the brightest star we can see (roughly -0.5) and Saturn is no slouch at 0.65 – and they’re in the southeast with two bright guidepost stars, Arcturus and Spica. Here’s what to expect.

Click image for larger version. (Prepared from Starry Nights Pro screen shot.)

December 11th isn’t so shabby either because we get a crescent Moon in the picture as well, though both Venus and Mercury have dropped  down a bit, you should still be able to find them both. Venus will be easy. Mercury – well, you may want to use binoculars, though it should still be visible to the naked eye if you have clear skies – and, of course, an unobstructed eastern horizon. It’s only about half a fist above the horizon at this point.

Click image for larger version. (Created from Starry Nights Pro screen shot.)

The Winter Solstice – Sure it happens every year but it always seems special – December 21

What’s so special about the Winter Solstice? Well, for me it’s a reminder that all life – you and I, plus every animal and plant on this tiny planet depend on the Sun. The Winter Solstice – as seen from the Northern Hemisphere –  reminds me of this because on the morning of December 21 the Sun will rise as far south as it gets. In the next few days it will start inching it’s way back north and that is certainly a good sign. Sure, our seasons lag behind the sky a bit. The worst of the winter weather is yet to come. But the fact that the Sun is on its way back is certainly an encouraging sign. More primitive societies that were in better sync with the natural rhythms of the sky, celebrated this time of year and with darned good reason.

Ceres is Ceres – but you can call it a dwarf planet

“Dwarf planet” was the category astronomers agreed upon in 2006 to fit objects that are big enough to be round, but too small to have cleared the area of their orbit of other objects. That’s what Ceres is and so is Pluto, and three other known objects.  It amazed me that this rather technical decision (I have greatly over-simplified the definition) caused such a stir because it demoted Pluto from planet to dwarf planet. These are simply classifications and in astronomy over time classifications get kind of messy. I mean, stars in the 19th Century  were classified in a nice alphabetical list by their spectra – but then we kept learning more and the list got screwed around  to anything but alphabetical: OBAFGKMLT. What’s more, our Sun – and many other stars that are among the larger ones, is called a “dwarf star!” Oh my – now that sounds illogical, if not offensive.

Oh – and Ceres, the first asteroid discovered (1802) – and largest (952km) – is still often referred to as an “asteroid” because it is a dwarf planet inside the orbit of Neptune where we usually find asteroids – arghhhhhhh! See why I want to just call it Ceres and be done with the naming thing ?  😉

Do click onthis for the full-size image - that's really Vesta as imaged by Dawn, but essentially this is an artists view of what it must have looked like as the Spacecraft orbited the asteroid.

Do click on this for the full-size image – that’s really Vesta as imaged by Dawn, but essentially this is an artists view of what it must have looked like as the Spacecraft orbited the asteroid.  (We didn’t send anyone along in another spaceship to take pictures of the two!)

But Ceres – and even brighter Vesta – have been the subject of an extensive examination conducted by the NASA  “Dawn” spacecraft.  It has spent a year examining Vesta and is now on its was to get up close and personal with Ceres. But you can beta it to it – you can see both Cere and Vesta from your backyard this month with nothing more than binoculars, a few charts, and some determination. Of course your view will be a bit less detailed. The two will appear as stars just below naked-eye visibility. And although it’s about half the size, Vesta is the brightest because it happens to be made of – or have on it’s surface – shinier material.

This is an excellent opportunity for you to test your skill with binoculars. This month they will both look like sixth magnitude stars and thus be easily seen in binoculars – but I won’t underestimate the challenge. The good news is they are well placed near bright, familiar stars and the brilliant planet Jupiter in the evening eastern sky. That makes it easy to find the general area in which to search. The bad news is there are lots of stars up there – especially when you look with binoculars – so you need to really study the charts before you go outside, then do  very careful observing. If you find it one night, it’s  fun to look again in a few days, or even a week or two – because they do change positions rather rapidly while the stars, of course, stay put.

Go here to get a printable chart of the Path of Ceres and Vesta over the next few months.

Now print this chart to use to mark your observations of Ceres and Vesta over the same period.  It’s a chart of the same area of sky covered by the previous chart, but with the position of Ceres and Vesta shown only for December 9, 2012 as viewed from mid-northern latitudes about four hours after sunset. However, while the orientation changes somewhat by date and time, it should serve to track Ceres and Vesta for December and January. Magnitudes of a few selected objects are given in parenthesis to help identify Ceres and Vesta. Before going outside to make your observation, study the chart and determine where you think Ceres and Vesta should be that night.

And as you look at Vesta, get this picture in your mind’s eye – and as you will see at the end, Ceres look a bit different, but how different – well, we’ll see when Dawn gets there!

And here’s the best view we have of Ceres as seen by the Hubble Space Telescope.

Images of the Asteroid Ceres As It Rotates One Quarter
Source: Hubblesite.org

Jupiter – let’s not forget the king of the planets

As some wag commented, our Solar Systems consist of the Sun, Jupiter, and some debris!

It is big – and only Venus outshines it, and yes, with careful viewing you can see one or more of the four Galilean moons using only binoculars. The key is to hold them steady and observe – don’t just look.  A “look” is what most people tend to do at first – that is, they hold the binoculars up and if, in 10 seconds or so, they have not seen the moons, they give up. That is not observing. To observe you need to look for at least a solid minute. That won’t guarantee you see the moons, but just taking a quick look can mean you easily miss them.

They may all be on one side of the planet and they constantly change their relationship with the planet and one another so that even with binoculars you can notice the difference over the course of a few hours. They will look like tiny stars, they will be close to the planet, and they will be roughly in a straight line that passes through the planet’s equator. This line will be pointing upward as the planet rises, level off when it’s near the mid-point of its arc across the sky, and be slanting down as it heads for the western hprizon.

The best way to prepare yourself for what to see – to check to see if you are seeing the right thing – is to go to the Sky and Telescope web site and use the javascript simulator there for your date and hour.  To do that, go here . With binoculars you want the right-side up view. With small telescopes it is much easier, of course, to see these Moons, but a telescope will change the orientation and this script allows you to change that orientation to match your telescope’s view. Here’s a typical example of what you will see.

Venus gives the Little King a morning kiss!

Looks eats in the morning sky of October 3, 2012. Click image for larger version – prepared from Starry Nights Pro screen shot.

Exactly how this event looks to you really depends on where you are. From my observation point on the Eastern Seaboard, I’ll catch Venus and Regulus very close to their closest approach with a separation of about 8 minutes of arc shortly after 4 am on October 3, 2012.  By the time the pair rises for West Coast viewers. the separation will be closer to 12 minutes. And, of course, those in “Down East” Maine will have a slightly better view of the event than I do.

But for all of North America and for some other places as well, it will be fun – weather permitting – to see Venus at magnitude -4.1 come so close to a first magnitude star, Regulus, at magnitude 1.34. That means Venus will be about 100 times as bright as Regulus, and I’m pretty sure this will make it impossible to see the star with your naked eye, though it should make a real cool view for binoculars and small telescope users. Regulus (Latin for “little king” or “prince.”) gets these close calls because it is so close to the ecliptic – the green line in our chart – which is the general area of the sky where the planets are found. On July 8, 1959, Regulus was occulted by Venus – that is, completely covered.  That will happen again on October 1, 2044. Of course the two aren’t really close. Venus is in our solar system and at this time about eight light minutes from us, whereas Regulus is 78 light years away.

How does this compare with the view of what is probably the best known double star, Mizar and Alcor in the handle of the Big Dipper?  Many people can split this pair with their naked eye, but they are  11.6 minutes apart.  So just considering the separation in minutes of arc, Venus and Regulus should be very, very difficult to split with  the naked eye. But Mizar and Alcor are  less than two magnitudes apart – a difference of about 6 times in brightness – and that makes it much easier to split them.

Still – I plan to watch starting about 4 am EDT when the pair are high enough above the horizon to see easily. As sunrise nears, the gap will widen to 10 or 11 minutes and separating them may get a bit easier as the glare of Venus will be diminished against the pre-dawn glow. If nothing else, this will certainly drive home the message of how quickly Venus is moving. By the next morning they are separated by more than a degree – still nice to see – and by October 8th or 9th you’ll be hard pressed to fit them both in the same binocular field of view!

In September 2012 – let Venus be your guide to the Beehive, crescent Moon, and Zodaical Light

Once again, Venus steals the show in the morning sky this September, while Mars and Saturn dance low in the southwest in the early evening. Jupiter crosses over into the evening sky, but just barely – it is still better seen during the early morning hours. In my book, the most fascinating and attractive naked eye challenge of the month will be seeing Venus  in the midst of the Zodaical Light – those minute solar system dust particles that in their own special way and time can mimic the display of the Milky Way.

Check out this wonderful photo of the Zodaical Light – and keep in mind that it was taken through the thin air and superbly dark skies of a mountain observatory and benefits from the camera’s ability to do a better job of capturing faint displays than our eyes. Still, it gives us a good idea of the shape and size of what we are looking for when we seek this elusive glow in our skies.

Zodiacal Light Seen from Paranal, European Southern Observatory.

Now I know the predawn hours are not for everyone, so let’s deal first with the continuing show in the southwest where Mars and  Saturn are still visible low in the sky shortly after sunset – and they still team up with Spica to make an interesting combination. What’s more interesting, however, is as the month goes on Saturn and Spica head  for the horizon pretty quickly while Mars will hold its own for the next several months, hanging out near the horizon and letting the background stars slide behind it.

On September 1, 2012 Mars, Saturn, and Spica will be near the horizon – but visible – 45 minutes after sunset in the west-southwest.

Prepared from Starry Nights Pro screen shot.

For the rests of the month Mars will remain at roughly the same altitude – betwen 11 and 13 degrees above the horizon about 45 minutes after sunset. However, Saturn and Spica swiftly fall out of sight. By mid-month Spica is a mere two degrees above the horizon and Staurn – barely visible – at about 7 degrees high. (Using binoculars will help locate it.)  By the end of September Spica has set at this point (45 minutes after sunset) and Saturn is a mere two degrees above the horizon – most likely too difficult to find.  But Mars’ rapid orbital motion carries it eastward as seen against the background stars which all appear to be moving westward – towards the horizon – because of the orbital motion of Earth.

Venus and the Beehive

Prepared from Starry Nights Pro screen shot.

From about September 9-18, 2012  you can watch Venus pass close enough to the Beehive (M44) star cluster for both to appear in the same low power binocular view. The most interesting view will come on the morning  of September 12 when they are joined by  a crescent Moon. Center Venus in your binoculars, the put it in the right side of the field of view and you should be able to see the Beehive. Put it in the left side of the field of view and you’ll see the Moon.

Oh – and on October 3, 2012 Venus will have an incredibly close visit with first magnitude guidepost star, Regulus. In fact they will be so close for those in mid-northern latitudes that  I doubt you’ll be able to separate them with the naked eye, though they should make a nice binocular – or telescopic – double! They should be about 8-minutes of arc apart – which means they’re closer together than Mizar and Alcor, the famous test of eye sight in the handle of the Big Dipper. I think you will separate them with binoculars, but the large difference in magnitude – Venus is -4.1 and Regulus about 1.3 = could make this a serious challenge. I should add, however, that Venus is moving quickly and  exactly how far apart the two  appear on this particular morning will depend on your location. If I move to the West Coast i get a larger separation. 

Basking in the Zodiacal Light

Prepared from Starry Nights Pro ecreen shot.

The second half of September 2012 will be a good time to start looking for that most elusive of Solar System sights, the Zodiacal Light – and Venus will help!  You actually have a brief window when it’s visible starting about two hours before sunrise and going to about  80 minutes before sunrise. After that the twilight will drown it out. Draw a line between first magnitude Regulus – near the horizon – and Venus. This line will tilt to the right (at least from mid-northern latitudes) and the Zdaical Light will be located along it since that is pretty much the line the ecliptic takes and the ecliptic marks the plane of our Solar System.  The ecliptic marks the general area where you are going to find most Solar System bodies – planets, moons, asteroids – and yes, tiny specks of dust that make up the Zodaical Light.

You don’t need a totally clear horizon to see the zodiacal light, or binoculars, but you do need total darkness and that means little-to-no light pollution and no  – or very little – Moon. In Septmeber 2012 the last two weeks fit the bill – from about Sept. 14-28. I feel I have a good shot at it from my favorite ocean-front observing point where I have a clear horizon to the east with no cities to create light domes there. Mornings in September and October –  or evenings in February and March – are the best times for folks at mid-northern latitudes to look for the Zodaical Light.

The Zodiacal Light is roughly the same intensity as the Milky Way, so if you can see the Milky Way from your chosen location, then you should be able to pick up this faint glow. Like the Milky Way, it stretches over a good deal of sky. It is widest near the horizon and gets narrower as it rises towards the zenith. You want to look for this starting 120 minutes before sunrise, but I advise you also allow at least 15 minutes to half an hour for your eyes to dark adapt. (For projects like this I frequently keep a red flashlight near my bed and use it to preserve my night vision when I get up.)  If you try to look for this later, you may confuse it with twilight. What we are seeing is sunlight reflecting off interplanetary dust particles – dust particles that orbit in the same plane as the planets – the area we call the zodiac – and thus the name for this phenomena, Zodiacal Light.

How high? How bright? How wide? All this depends on your conditions – and even in an area where theere is little or no light pollution, it will vary. All nights are not equally transparent.  But you do want to avoid the Moon and it will come back into the equation by the 28th – but don’t worry. If you miss it this month, October and November are also good months to see it. And if you wish to see it in the evening sky, March and April are good.

If you see it, reflect on this explanation from Wikipedia:

The material producing the Zodiacal Light is located in a lens-shaped volume of space centered on the Sun and extending well out beyond the orbit of Earth. This material is known as the interplanetary dust cloud. Since most of the material is located near the plane of the Solar System, the zodiacal light is seen along the ecliptic. The amount of material needed to produce the observed zodiacal light is amazingly small. If it were in the form of 1 mm particles, each with the same albedo (reflecting power) as Earth’s Moon, each particle would be 8 km from its neighbors.

For the metrically-challenged (that includes me) that means one dust particle every five miles! And each particle is tinier than a bird shot – way tinnier than a BB. And that causes all that light?! Awesome!

August 2012 – Mars, Saturn, Spica in the west – and a spectacular Perseids shower

Should you watch the planet show in the West in the evening? Or the meteor shower in the morning? Why not both? And if you’re getting up early to see the Perseids at their best, be sure not to miss brilliant Venus and Jupiter – well, how could you?

Over in the west we have Mars showing you how fast a planet can appear to move as it runs between  Saturn and Spica – over a period of three weeks making a colorful red, blue and yellow display.  And all over the sky for several days this month you are likely to pick up a brilliant, Perseid meteor – but particularly on the morning of the 12th of August with the 13th a good back-up – and this year’s show should be especially good because the Moon will not put in an appearance until early morning and will not be bright enough to ruin the show.

Let’s start with the west – week-by-week the changing scene will look like this low in the southwest about an hour after sunset:

The circle is 7 degrees – roughly what you can expect from a low power binocular view.

 

A fun night because a young, crescent Moon joins our trio.

You will need a clear and unobstructed  western horizon for this one because these three objects are roughly 10 degrees – one fist – above the horizon. (Early in the month they’ll be a bit higher – late in the month they get quite low.  Now what I love about this event is it demonstrates three things –

  • Color in the sky – Saturn is yellow, Mars, Red, and Spica blue. But these colors are subtle. You’ll see them better if you use binoculars and you might want to review this post on star colors to better know what to expect.
  • Perception and the effect of motion – from night to night Saturn will hardly appear to change positions relative to the background stars at all,  and Spica won’t  change – but Mars will whip right along and this will be amply clear as you check it’s position against the other two.  The reason is simple – Mars is much closer to us at about 158 million miles; Saturn is about 939 million miles and, of course, Spica is so far away we measure its distance in light years – 263.
  • The time dimension is on display as well – Mars is roughly 14 light minutes from us, Saturn is  well over a light hour, and Spica  263 light years. So what appears to be a two dimensional scene is revealed to be three dimensions as you observe the rapid motion of Mars and picture the solar system – and when you put your mind to it, you understand that the instantaneous nature of the scene is an illusion – that you are really looking into the fourth dimension and what happens simultaneously from your perspective is really happening at much different absolute times.

To help grasp the situation, take a look at this Orrery view of the Solar system for August 7. Keep in mind two things. The east-to-west motion we see as the night goes on is due to the spinning of the Earth.   The night-to-night westward – downward – drift of all  is caused by the motion of the Earth in its orbit around the Sun.

Orrery view for August 7, 2012, (Click image for larger version.)

The yellow arrow in the image above shows our view of Mars and Saturn in the evening sky. As the Earth rotates counter clockwise on any given evening, first Jupiter, then Venus come into view in our morning sky – red arrow.  If you then picture the Earth moving ahead in its orbit it’s not hard to understand why Saturn and  Mars will eventually be lost from view, while Jupiter will appear earlier each evening. Venus is a bit more complex. It too will get lost in the glare of the Sun, but since it is moving faster than us the change will appear to take place fairly slowly. Maybe I’m just slow, but it has taken me years to move from these abstract representations of what we see in the sky and how the planets are moving, to get to the point where I can look up and have a genuine, intuitive sense of what’s going on. Very satisfying and worth the effort, but even if you don’t do that, it’s a wonderful show! (The Orrery view is obtained from Solar System live web site. Go there and play with the dates to see the changing motions of the planets.)

Perseids in the morning

OK – so much for the evening sky. The morning sky is really spectacular because we’re looking at a section of sky that contains a lot of our brightest stars and  two terrific star clusters, plus the two brightest planets. What backdrop for a brilliant meteor shower!

The red oval represents the area opf the sky from which the Perseid meteors appear to radiate – however, they can go in any direction from here and might appear any where in the sky. (Click image for larger version. Prepared from Starry Night Pro screen shot.) Here’s a quick guide.

Perseids – a quick guide

When:

The night of  August 11-11 starting about 90 minutes after sunset, but best after midnight. And if that night is likely to be cloudy, the next night of August 12-13 might prove to be just as good, but the best chance looks like the 11-12. (There’s no doubt you should see meteors either night – but there is doubt as to exactly when the shower will peak.)

Where:

Any place you have a clear and dark sky – the more horizon visible the better, but in truth you can only look in one area at a time, so a clear, dark sky to the northeast is best. While a Perseid meteor can appear anywhere in the sky, your best chance to see  several will be to scan the sky to the northeast in the general vicinity of the “W” of Cassiopeia.  However,  you don’t have to fixate on one region. Get comfortable, look high in the northeast, and from time to time look around to different sections of the sky to enjoy the sights and stay alert. My most memorable Perseid skimmed the horizon to the north.

What can you expect to see?

Under the best conditions at the peak of the shower, you can expect to see between one and two meteors a minute! But I never seem to achieve those best conditions, so I don’t raise my hopes too high. I’m just sure I’ll see many more meteors than normal, but fewer than I would in a year when the Perseids are at their very best.  To put numbers to it, I’d be delighted if I averaged one every five minutes. For everyone, everywhere, the intensity of the annual Perseid “meteor shower” is in a down swing, but because we’ll have little interference from the Moon, this should be a better than average year.

Meteors and meteor showers are fun if for no other reason than they are a chance to see something happening in the sky. Much of what we look at doesn’t change – or rather changes so slowly we don’t notice the change. Meteors, on the other hand, demand that you be looking in the right place at the right time. Only on the very rare, very bright meteors do we actually have time to alert others and have them turn their heads and see what we see.  And what we see is a space event happening closer to us than any other natural one. What’s more, meteors can have real scientific value.  They are viewed by some as our cheapest “space probe.” They are relatively pristine bits of matter left over from the early days of the solar system and so can tell a story to those who know how to read them.

Meteors – “falling stars ” – can be seen any time. You don’t have to wait for a “shower” like the Perseids; you just have to be lucky. But they are most frequent at certain times in the year when the Earth happens to be plowing through a meteoroid-rich area.  We call this occasion a meteor shower. (For your dictionary: A meteoroid is a small bit of space rock that becomes a meteor when it collides with our  atmosphere and heats to incandescence as it descends towards Earth. When it gets here – which is rarely as anything except fine, incinerated dust – it is a meteorite. )

The reason for a shower such as the Perseids is that we are passing through the debris trail of a comet. Think about it. The general model for a comet is a “dirty snowball,” and as that dirty snowball nears the Sun it melts, and as it melts it leaves a trail of dirt particles behind it – particles that remain in orbit until something like the Earth sweeps by and captures some of them with its gravity.

The comet itself can vanish entirely – but the result is a river of space dust – a river that is most intense nearest where the comet actually was.  That’s why there are some years – the 1990s in the case of the Perseids – when the meteor shower is more intense than others.  Now we are in a period when we are passing through the trail of the comet that creates the Perseids at a point where that trail is relatively sparse – so there will simply be fewer Perseids than there were  15-20 years ago.

That trail is not encountered all over the sky. It collides with our atmosphere near a particular point in our sky. That point is called the radiant – you might think of it as a hole through which the Perseids fall – and in the case of the Perseids, it appears to be in the constellation Perseus.  But we don’t see all the meteors at this point. We see a meteor only when its collision with our atmosphere is intense enough to make it burn up. The faint meteors we see are made by a speck of dirt about the diameter of a pencil lead. The brightest ones are caused by something about the diameter of the pencil’s eraser.  In either case it will, for all practical purposes, burn up entirely in our atmosphere – 50 to 75 miles up – and nothing significant will remain for anyone to find on Earth. But exactly where it burns up is another thing. That’s why we will see a sudden flare – a falling star – anywhere in the sky.

And that’s awesome! Consider this: If someone struck a match 50 miles away would you see it?  Yet a grain of sand, hurtling into the atmosphere, shows us such a brilliant light we can’t miss it!

When you are watching for Perseids, you don’t have to look near the radiant point, though you will see more there.  A meteor can flare up suddenly anywhere and appear to draw a short (usually 5-10 degrees long) straight line across the dome of the sky. (Bright ones may actually leave a trail, which you can see for a few seconds with the naked eye or longer with binoculars.) If we trace a line backwards along the meteor’s trail we will see it comes from the area near the radiant point.

In the early evening, that Perseid radiant point is low in the northeast. That means nearly half the meteors that are radiating from it are happening below our eastern horizon. That’s why the shower is best in the early morning hours when the radiant is high in our sky. If the radiant is overhead, then we have nearly doubled our chances of seeing a meteor.

There are many meteor showers in the course of a year and some are better than others. The Perseids is one of the most reliable ones and happens to come at a convenient time for northern hemisphere observers when it is comfortable to be out at night, lying on the ground, and looking up.

Personally, I don’t like the word “shower.” It immediately gives the impression that what we are going to see will be more intense than what most of us actually experience. I prefer calling this a meteor “event.” But, we have been calling such events “showers” for years, and too often they are hyped in the press and then people are disappointed when nothing like a shower occurs. So keep your expectations realistic and you won’t be disappointed.

In the final analysis there’s only so much time you can spend lying on your back gazing at the starry sky; though I very much enjoy that time, it’s made much more enjoyable by knowing that at any instant there’s a heightened likelihood that I will see a bright meteor.  That – and the summer Milky Way – make looking for Perseids in a dark and moonless sky always worth the effort for me.

All square on a 2012 July morning with Jupiter, Venus, the Moon and Aldebaran

That is, all will be square in the morning sky  July 15, 2012 and in the evening sky July 24, 2012 – two dates to keep in mind this month. However, Mercury puts on one of its now-you-see-it, now-you-don’t shows the first week of the month in the west and all – Venus and Jupiter flirt with the gorgeous star clusters – the Hyades and Pleiades – in the morning sky.  Here was the scene from  my driveway this morning, July 1, 2012 – typical of the whole month and quite dazzling!

I snapped this about 4 am on July 1, 2012 looking east from 42* N latitude. That’s Jupiter at about magnitude -2 on top, and Venus at -4.4 on the bottom. Aldebaran was still hidden by the trees and my skies were too murky – and twilight already too advanced – to pick up the Pleiades easily, though scanning this area with binoculars revealed them and the Hyades. (Click photo for much larger image.)

Meanwhile, over in the west you still have a chance to catch “fleeting” – make that “fleeing” – Mercury. Here’s where to find it.

At magnitude .6 Mercury is significantly brighter than the other stars, although this image makes it seem less. Use binoculars to find it – though you should be able to see it with your naked eye. Click image for a much larger view. (Prepared from Starry nights Pro screen shot.)

OK – about  the “all square” business

It’s really not a square, but it should be a pretty rectangle that will vary a bit depending on just where you are located and exactly when you look. On the morning of  July 15 the eastern sky should look something like this – at least for those in mid-Northern latitudes. With an unobstructed horizon and clear skies the best view will be about two hours before sunrise. After that it becomes a race – planets and stars all climbs higher and thus are easier to see as time goes by – but, of course, the skies also get lighter as summer twilight starts early.

Click image for a much larger view. (Prepared from Starry nights Pro screen shot.)

 

In fact, all month Jupiter and Venus turn up the dazzle in the early morning sky, playing in the general vicinity of  the Pleiades and the Hyades. An unobstructed eastern horizon helps, as do binoculars if you want to get a good look at the two star clusters even in twilight.  By the end of the month Jupiter will be in the Hyades and Venus will have dropped quite a bit lower – yet the whole star show will be significantly higher at the same hour. Fun to catch it several times to observe the changing dynamics of our solar system playing against the backdrop of the rest of the universe.

And in the evening sky

The second “square” feels a bit like a mirror image. I don’t think it will be as dazzling because the planets involved simply aren’t as bright  and the Moon will be significantly brighter. Still, this one takes place in the early evening of July 24, 2012 and involves Saturn, brightest at magnitude .77, Mars at magnitude 1, Spica at almost the exact same brightness as Mars, and a 6-day-old Moon.

Click image for a much larger view. (Prepared from Starry nights Pro screen shot.)

 

 

 

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