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


Photo of the Week. Vesta, the brightest asteroid and the fourth found, 500 kilometers in diameter and averaging 2.4 times Earth's distance from the Sun, moves through central Gemini on January 21, 2006. Occasionally visible to the naked eye, here it shines at magnitude 6.6, just fainter than the formal limit. Castor and Pollux shine at far left, Castor on top.

Astronomy news for the week starting Friday, February 17, 2006.

The Moon begins our week in its waning gibbous phase, passes third quarter the night of Monday, February 20 (about the time of Moonrise in North America), and thereafter wanes as a thinning crescent, rising ever later. The night of Friday the 17th sees the Moon rising just to the east of the star Spica in Virgo. Then take a look as the Moon lies to the southwest of Jupiter the morning of Sunday the 19th, and to the southeast of the planet the following morning, before plowing down through the heart of Scorpius. The morning of Tuesday the 21st, the Moon will be just to the west of Antares, close, though not (for those of us in North America) replicating the more intimate passage of last month. (The star is occulted as seen from Australia, while Spica is earlier occulted as seen from parts of Africa.) Finally, the morning of Friday the 24th, the waning crescent can be seen down and to the right of Venus.

Venus tops the planetary scene, as on Friday the 17th it reaches its greatest brilliancy of the year. While seen as a crescent through the telescope (the current positioning causing us to view mostly the nighttime side and just a piece of the daytime side), Venus is so close that it now reflects its maximum light to us. The fading will for a long time be un-noticeable. Rising now in a dark sky just before 4:30 AM, the planet will for a time get higher before dawn takes over (the combination of Venus against growing twilight glorious to see). Be sure also to admire Jupiter. Now rising around midnight in Libra, the giant planet is making the transition to the evening and crossing the meridian to the south at daybreak, giving the morning sky two great lights.

Early evening gives us another pair of planets to watch. Moving into mid-evening's western sky, Mars (in Taurus) transits at sunset, but does not set until past 1 AM, after Jupiter rises. Far to the east is Saturn, in Cancer, which transits to the south about 10:30 PM and lies near the Beehive cluster (Mars, in parallel, visiting the Pleiades). If you have a clear western horizon, in fading twilight you might also spot Mercury, which is making its winter appearance, its maximum eastern elongation (18 degrees) taking place on Thursday the 23rd.

Again we look to mighty Orion, which in mid-evening stands midway up the southern sky, the constellation filled with brilliant blue-white stars and bejewelled with one reddish one, the supergiant Betelgeuse. Many of the constellation's stars share their place and time with each other as part of a loose, physically-related, "association." Scorpius (which holds Antares, the other bright red supergiant of the sky), Centaurus, and Perseus are similar. Gradually, as spring approaches, the Hunter will tread to the west, he and his bright entourage to be taken over -- temporarily (he will be back) -- by the Sun.
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