Skylights featured on Astronomy Picture of the Day

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Skylights featured five times on Earth Science Picture of the Day:
1 , 2 , 3 , 4 , 5

Cloud shadows

Photo of the Week. Cloud shadows and fingers of sunlight proclaim the glory of the sky.

Astronomy news for the two-week period starting Friday, March 17, 2006.

Read A Minute with Jim Kaler, a brief interview on the outer bodies of the Solar System that appears on the U of I home page.

Skylights will next appear on Friday, March 31.

The fortnight sees the Moon in its waning stages, beginning with the waning gibbous. Passing third quarter on Wednesday, March 22, the Moon then goes to the waning crescent, finally passing new on Wednesday the 29th. You might then get a glimpse of it as a slim waxing crescent in evening twilight the night of Thursday the 30th.

Look for the Moon to the south of Jupiter the morning of Sunday the 19th, then see it to the west of Antares in Scorpius the morning of Monday the 20th and to the east of the red supergiant the following morning. The morning of Saturday the 25th, the Moon not only passes, but occults Ceres, the largest asteroid (the event sort of visible only on the east coast). The better target is Venus, the Moon to the southwest of the brilliant planet the same morning (the 25th), while to the southeast of it the following dawn. On the 25th and the 27th, it also respectively moves to the south of Neptune, then Uranus, the two outer planets having both moved into the morning sky. Finally, you might see it to the right of Mercury in dawn the morning of Monday the 27th.

Coupled to the penumbral eclipse of the last full Moon is a total eclipse of the Sun at the time of new Moon, on Wednesday the 29th, but one that will sadly miss all of North America, as the path runs from eastern South America then across Africa, southern Europe, and central Asia.

We fare better with the planets, as Venus reaches its greatest western elongation 47 degrees to the west of the Sun on Saturday the 25th, the brilliant body rising around 4 AM, half an hour before the onset of twilight. At almost the same time, Saturn - - nicely visible in Cancer and high to the south at 8:30 PM -- sets. Rising ever earlier, Jupiter (still in Libra) now comes on the scene around 10 PM, while transiting the meridian as dawn approaches, about an hour before Venus rises. Finally, look for Mars (in Taurus) to the west as the sky darkens, the red planet still not setting until after midnight.

The biggest planetary news is of planet Earth. At 12:26 PM Central Time (1:26 PM EST, 11:26 AM MST, 10:26 AM PST) on Monday, March 20, the Sun passes the Vernal Equinox in Pisces, which begins spring in the northern hemisphere, fall in the southern. On that day, the Earth's axis is perpendicular to the line to the Sun, the Sun is overhead at the Earth's equator, and rises due east and sets due west. Days and nights are also closely equal at 12 hours apiece, and ignoring refraction in the atmosphere and the finite diameter of the Sun, the Sun rises at the north pole and sets at the south pole to initiate the long south polar night.

While not on everyone's lips (except for those watching the television program "Jeopardy," which recently featured it in a question), this is a fine time of year to admire (as best you can), Monoceros, the Unicorn, which lies to the east of Orion and between Sirius and Procyon. While seeming to be a rather blank area of sky, Monoceros, falling in the faint winter Milky Way, is filled with fascinating young stars and nebulae, and is a rich ground for the dedicated amateur star gazer.
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