Astronomy From Your Back Yard - 11/17 to 11/23 2010

Thursday, November 18 2010 @ 12:57 pm EST

Contributed by: dgrosvold

By Dave Grosvold

Unfortunately, business travel demands have kept me away from this column for a couple of weeks. It's good to be back! Well, it looks like there will be some clear skies and great opportunities for night-time sky watching Thursday through Sunday this week. To get a better idea how the night sky viewing will be for the next two evenings, check out the Fort Smith Clear Sky Chart. This chart will tell you how dark the sky will be, when you can expect cloud cover during the night, and what transparency and seeing conditions are expected.

On Wednesday evening, Jupiter will be slightly higher and about 20° to the right of the waxing gibbous Moon. The Moon reaches the Full phase on Sunday, November 21 at 11:28 AM CST. As a result, it will be a bright beacon in the night sky all week, washing out all but the brightest stars and planets. There will be early-morning dark skies late this week (Thursday & Friday,) as the Moon sets at about 3:00 AM CST on Thursday morning, setting about an hour later each morning until later in the week when it remains visible the entire night.

The bright star Vega in the constellation Lyra remains the brightest star in the west-northwest these evenings. The brightest star higher above it is Deneb in the constellation Cygnus. To the left of Vega lies the third member of the Summer Triangle, Altair, in the constellation Aquila. Both the cool crisp air and the Summer Triangle low in the western sky are sure signs of approaching winter.

For a challenge this week, use binoculars to scan for Mercury very low in the southwest less than a half hour after sunset. Mars is less than 2° to Mercury's upper right. If you place Mercury in the lower left of the field of view, you should be able to detect fainter Mars above and to the right.

By 9:00 PM CST Saturday, November 20th, the constellation Orion has risen in the east-southeast. Look for it far below this evening's high, bright Moon. The three unmistakable belt stars in Orion will be lined up vertically, with the bright blue-white star Rigel on the right, and fiery-red Betelgeuse on the left.

Halfway between Betelgeuse and the Moon is another bright red star, Aldebaran, in Taurus. Draw an imaginary line from the Moon down through Aldebaran to Betelgeuse, and then imagine a line perpendicular to the first one, to the left of Adebaran you should see the bright yellow star Capella, in the constellation Auriga.

On Sunday evening, the Full Moon passes just below the Pleiades (M-45,) an open cluster in the constellation Taurus. At closest approach the Moon is just slightly more than 4° from the center of the Pleiades, or just over the width of two fingers held at arm's length.

This week, Venus is rising ever higher at dawn in the east-southeast. Look a little above it or to its upper right for much-fainter Spica in Virgo. Look higher (about 16°) above it for Saturn. Saturn's rings have widened to a tilt of about 9° from edge-on. The best time for observing Saturn with a telescope is about an hour before sunrise, or about 6:00 AM local time, when the planet will be above the “muck” -- the haze and turbulence found close to the horizon.

You may also be able to catch a couple of bright Iridium Flares this week. Iridium 41 flares to -6 magnitude at 4:51 AM CST on Thursday morning. Look for it in the south at an altitude of 21°. Then on Sunday evening at 5:58 PM CST, you can catch Iridium 66 flare to magnitude -7 in the south at an altitude of 33°. Early on Monday morning, Iridium 62 flares to magnitude -4 nearly overhead at an altitude of 59° in the north-northwest. There are a several other chances to catch Iridium Flares, this week albeit at dimmer magnitudes. Be sure to check the web site at Heavens Above for times and positions.

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