Skylights featured on Astronomy Picture of the Day

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Skylights featured nine times on Earth Science Picture of the Day: 1 2 3 4 5 6 7 8 9

Anti-crepuscular rays

Photo of the Week. Subtle, fleeting sunbeams ("anti-crepuscular rays") are caused by cloud shadows. The reverse of the usual sunbeams that seem to diverge from the Sun, after passing overhead they appear converge to a point near the opposite horizon. The evening waxing gibbous Moon watches the show.

Astronomy news for the week starting Friday, November 5, 2010.

Our week begins with the new Moon, which takes place the night of Friday, November 5. The first glimpse of a very thin crescent might be had under near- perfect conditions in twilight the evening of Sunday the 7th, with the Moon making its appearance just down and to the right of Mars, the two making a nice triangle with Antares (of Scorpius), which will be off to the left, the star notably brighter than the planet. Binoculars, however, are a requirement, as the low sky will be so bright with twilight.

And too bad, as it's such a nice pairing, Antares sharing Mars's name, "Ant-Ares" meaning "like Mars," "Ares" the Greek version of the god of war. Formal conjunction between the two takes place on Tuesday the 9th, Mars passing 4 degrees north of the star. The following nights become increasingly better for the Moon as the crescent, climbing ever- higher night after night, heads towards first quarter on Saturday the 13th.

Mars can for a time be forgotten. Not so Venus, which is now beginning to claim its dominance of the morning sky, the brilliant planet rising just about the time dawn begins to light the eastern horizon. Getting rapidly higher and brighter, it will achieve maximum brilliance for this round on December 4, making a much finer sight than it did in early autumn's evening performance. Before Venus makes its mark, you can always admire Saturn, which now rises around 4 AM STANDARD time (a good time to note that the clocks get turned back on Sunday the 7th).

Earlier, in the evening, we still have Jupiter to contend with, the bright planet (second only to Venus and close to the Aquarius-Pisces border) crossing the meridian to the south about 8:30 PM. With it (and neighboring Uranus to the northeast) setting around 2:30 AM, the sky is planetless for more than an hour before Saturn rises. Moving farther out, not that anyone will much notice, dim Neptune stops its retrograde movement on Sunday the 7th, and begins once again its agonizingly slow easterly trek against the stars of extreme northeastern Capricornus.

Speaking of which, the early part of the week, with the Moon more or less out of the way, is ideal for searching for such faint constellations. The most obvious configuration is the "Y"-shaped "Water Jar" of Aquarius, which around 7 PM sits on the meridian about half way up the sky, Capricornus down and to the right, Pisces up and to the left. The dark sky might also help in picking up some meteors from the two Taurid streams, which occupy much of the month, giving us perhaps 10 an hour after midnight. They seem to be related to the very-short-period Comet Encke, which goes around the Sun in but 3.3 years.
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