Saturday, November 24, 2007

Clear Skies....Get Yer Coat On and Get Out There!

We're in for a few days of clear skies, and even though the nearly full Moon will dominate the entire night sky for the next few days, you should bundle up and get out for a little bit of winter sky orientation. The Moon's light will make observation of Comet Holmes difficult if not impossible.
Moonlight will wash out all but the brightest stars, but you can use that fact to help you locate the bright stars of the "Winter Hexagon".
Refer to this PowerPoint file (The Winter Hexagon) to learn to know the 6 bright stars that mark the winter skies. (if you need a PowerPoint viewer, get it here) Tonight the Moon is between Aldebaran and Capella, and over the next few evenings it will work its way toward a close encounter with Mars - between Capella and Pollux - on the night of 11/26.
For good viewing you should have a clear view of the sky to the EastSouthEast of you, and be as far from artificial lighting as you can get. Give your eyes about 15 minutes to adjust to the dark once you're outside (that's why you want yer coat on!)
And I've turned on the comments option, so let everyone else know if you get out there, and what you're able to see.

Sunday, November 11, 2007

Comet Holmes

If you haven't seen it yet, get out to see Comet Holmes tonight. The image above will help you find it if you know Cassiopeia, or you can check out this larger sky chart here to orient yourself with the horizon and more stars.
A comet's tail trails off away from the sun, blown by the solar wind - it has nothing to do with the direction the comet is moving - (see this animation to understand better). Our present comet/Earth/Sun alignment gives us a rare "head-on" view (a fuzzy circle), rather than the more familiar side view (the tail is behind the fuzzy spot we're seeing).

The excerpt below comes from this Sky and Telescope article...

he comet remains as bright as ever to the naked eye, though its average surface brightness continues to drop as it enlarges. As of last night it was 14 arcminutes wide, or nearly ¼° — half the apparent diameter of the Moon. During this dark-of-the-Moon period (which will end around November 15th), seize whatever chance the weather allows to show family, friends, and strangers something memorable. This is how new amateur astronomers are born.

Saturday, November 10, 2007

Recent Atmospheric Optics: Glories and Sundogs!

On our approach to the Denver airport 2 weeks ago, Mr. Patrick and I were treated to an interesting optical effect called a "glory", and we've posted a video of it on Youtube.
You can read about how the glory forms here

While enjoying a few days on the road during this past week, I got these shots of some nice sundogs over the Long Island Sound: and a wider view here:

Sundogs are about 22 degrees (two fists or one outspread hand) on either side of the sun.

You can read about how sundogs form at Les Cowley's atmospheric optics page: