The Sky This Week : September 24 thru October 1, 2013 !

The Sky This Week, 2013 September 24 – October 1
Stargazing fun before the Sun
NGC7789_130815_01small.jpg

NGC 7789, “Caroline’s Rose Cluster” in Cassiopeia

Discovered by Caroline Herschel in 1783. She was the sister of and observing assistant to
the renowned English astronomer Sir William Herschel.

This image was made at Fishers Island, NY, 2013 August 15 with an 80mm (3.1-inch) f/6 refractor
and a Canon EOS Rebel T2i DSLR.

The Moon greets early risers this week as she passes nearly overhead among the stars of the Great Winter Circle. Last Quarter occurs on the 26th at 11:55 pm Eastern Daylight Time. Look for Luna close to the bright star Aldebaran before dawn on the 25th. Three mornings later she will be five degrees south of bright Jupiter. By the end of the week she will be in the vicinity of ruddy Mars and the bright star Regulus in Leo, the Lion. This is a good time to take advantage of the late sunrises and generally calm air available in the morning hours to take a look at the Moon before heading off to work or school. It’s a chance to see many of the features that many of us are familiar with during the Moon’s waxing phases in a completely different light. This is often the best time of the day for close-up observing since the turbulence in the atmosphere is usually at its minimum after a night of radiating ground heat into space. You can also observe the Moon until well after sunrise. Snap a picture of the Moon with your smart phone to explain to your boss or teacher why you’re a little bleary-eyed in the morning!

As the Moon moves into the morning sky we once again have a chance to explore the wonders of the “deep sky” along the star clouds of the Milky Way. At the end of evening twilight, which now occurs at around 8:30 pm EDT, the splendor of this faint band of ghostly light may be seen bisecting the sky from southwest to northeast if you’re well away from city lights. Directly overhead you’ll find the three bright stars of the Summer Triangle, Vega, Deneb, and Altair, and if you look near the middle of these three stars you’ll see the Milky Way appear to split into two distinct branches. The dark rift that seems to cause the split is actually part of the vast cloud of cool gas and dust that’s distributed along the Galaxy’s rotational plane, and it’s blocking the light of more distant star clouds behind it. Under very dark skies you can trace out dozens of smaller eddies and blobs of similar darkness as you sweep from overhead down to the “teapot” asterism of Sagittarius with binoculars. Examination of some of these spots with a telescope shows them to be almost totally devoid of stars, but hidden within their depths are the embryos of new stars yet to shine. Eventually the new stars will become luminous and drive away the dark clouds, revealing a cluster of bright young stars similar to the dozens of others sprinkled along the Milky Way’s length.

Evening twilight is still the best time to see the brilliant glow of Venus, but the dazzling planet is now gradually beginning to make inroads into the darker post-twilight sky. Venus is still located in the southwestern sky, and this week she is beginning to draw a bead on the ruddy star Antares in the constellation of Scorpius. You may recall that she passed slowpoke Saturn last week and has now left the ringed planet far back in her wake. If you want to catch a last glimpse of Saturn you’d better hurry; he sets by 8:30 pm.

My mornings are starting much earlier than usual these days thanks to the lure of observing Jupiter in the pre-dawn sky. Fortunately if I’m up by 5:30 I have a solid hour to enjoy the giant planet in my telescope before the sunrise washes out the view. Jupiter’s cloud belts are well-defined and prominent so far this apparition, and the famous Great Red Spot seems to be a bit greater and redder than it was last year. This feature, which is thought to be a huge storm in Old Jove’s atmosphere, has persisted for some three centuries with varying degrees of prominence. For the past few decades it has been rather pale and indistinct, but it has become much easier to see in small telescopes in the last few years. It will be awhile before it reaches the deep brick-red color that characterized it in the late 1800’s, but it’s heading in the right direction!

Mars offers another pre-dawn target for the telescope, but it is not going to rival Jupiter any time soon. The red planet is still on the other side of the Sun from us, so he offers little more than a small pink-hued disc in the high-power eyepiece. However, by the end of the week a comet known as C/2012 S1 (ISON) will pass close to Mars and could be quite a spectacular sight in the martian sky. It will be the subject of intense scrutiny by several spacecraft orbiting and roving the planet’s dusty surface. Comet ISIN may even become a naked-eye object in our sky by late fall and early winter, but more on that in a future edition.

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