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  • Rapt in Awe

    My Journey through the Astronomical Year

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

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

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

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

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

(click for larger chart)

(click for larger chart)

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

(click to enlarge)

(click to enlarge)

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

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

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

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

(click to enlarge)

(click to enlarge)

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

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

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

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

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


One Response

  1. […] shortest night of the year, but it is chock full of planets – all of them! ( Yes, we had a similar opportunity in May, and that was great fun – but it gets a tad better in June and there’s something a bit […]

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