Astro Bob A look at celestial happenings in the Northland and beyond Bob King View my profile Click here to view previous posts or additional resources

Starry, starry nights

The moon rises last night over Lake Superior and a lucky boater. Credit: Lyle Anderson

With my time committed to other activities in the next few days, I thought we'd take a breezy look at this week's upcoming astronomical events in one fell swoop. On tap are a playful game of cat-and-mouse among the evening planets, a Jupiter-moon conjunction and a surreptitious star in the north. In addition, we'll check out the final constellation of the Summer Triangle, Aquila the Eagle.

Tuesday night July 27

Maps created with Stellarium

Venus, Mars and Saturn gather together ever more closely in the western sky during evening twilight. Watch the positions of Mars and Saturn change quickly over the next few days as speedier Mars looks to overtake the ringed planet. Venus is always easy to see nearly due west 45 minutes after sunset. Slide up from Venus to locate the others and keep binoculars handy just in case. If you're into extreme challenges, try to spot Mercury sitting right next to the star Regulus a considerable distance to the lower right of Venus and very near the horizon (see below).

A lake or prairie horizon to the west-northwest is your best bet for catching Mercury's close conjunction with Regulus in Leo Tuesday evening. Look about a half hour after sundown.

Wednesday night July 28

Cassiopeia helps to direct you to low-flying Capella nearly due north at nightfall.

One of winter's brightest stars is poking around the northern horizon in late July. Capella in the constellation Auriga is due north and visible from the northern states and southern Canada a few degrees above the horizon. In late July it reaches what astronomers call lower culmination -- its lowest point in the sky. It's one of the few really bright stars that doesn't set for skywatchers in mid-northern latitudes. If you have a clear horizon to the north and haze-free skies, look for it around 10:30 p.m. local time.

Thursday night July 29

Altair is the bright star in the head of Aquila the Eagle. It's accompanied on either side by two stars I've always seen as "guardians" or keepers of the eagle named Tarazed and Alshain. The latter is Arabic for peregrine falcon. Tarazed is a 4th magnitude star, Alshain a 3rd and Altair a 1st -- a fine group to use to get to know star brightnesses better.

With the moon now waning and soon to exit the evening sky, now's a good time to add Aquila (AK-will-uh) to your list of summer constellations. Look high in the southeastern sky and use the chart provided to find it. Aquila is Latin for Eagle, and if you connect its starry dots, you'll find it bears a good resemblance to a stick-figure bird with fully-spread wings. The constellation's brightest star is Altair, which forms the southern vertex of the prominent asterism the Summer Triangle.

This wide-view chart shows how Aquila connects to the Summer Triangle. Vega at top is nearly at the top of the sky around 11 o'clock in late July.

Friday night July 30

Mars and Saturn are in conjunction tonight to the upper left of Venus. Can you see both without binoculars? This map shows the sky as you look west about 45 minutes after sunset.

Lots happening tonight with planets. Mars are Saturn are less than 2 degrees apart and make a fine, close pair. Mars is much closer to the Earth than Saturn and moving quickly eastward (to the left) in its orbit. Saturn is moving east too, but much more slowly, allowing Mars to overtake beginning tonight. Can you still see Mars' red color? If you have difficulty with the unaided eye, it should be no problem in binoculars. If you stay up until 11 or so, you'll catch the waning gibbous moon in the southeast in close company with brilliant Jupiter.

If you look low in the southeastern sky around 11:30 p.m. Friday, you'll see the moon has a bright companion.

Posted by: rking@duluthnews.com on 7/26/2010 at 11:12 PM | Comments (0) | Permalink | Edit

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