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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: 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.

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4 Responses

  1. […] Special note for May/June 2011 Saturn kisses Porrima, moving so close in early June 2011 that you may just be able to squeeze the two in a high-power, wide field eyepiece enjoying the beauty of Porrima’s nearly identical white globes and Saturn’s always spectacular rings at the same time. For details, see this pos ton “Prime Time: Your Journey through the Astronomical year.“ […]

  2. […] Oh – and for more details on the May planet show, go here. […]

  3. […] for spring on the northwest coast of Oregon.  The first evening I tore myself away from the current close encounter of Saturn and Porrima to take a look at Algorab, the haze was so thick and the seeing so poor that I couldn’t even […]

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