Skylights featured on Astronomy Picture of the Day

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


Photo of the Week.. Planet Earth: Misty beauty fills the Swiss Alps, a lonely river winding between them as they march off to the horizon.

Astronomy news for the week starting Friday, December 5, 2003.

Welcome to the last month of the year, and to the approach of winter. The Moon goes through its full phase on Monday, December 8, and in honor of the season is known as the "Cold Moon," or the "Long Night Moon." Nights are getting longer, days shorter (for us in the northern hemisphere), as the Sun is already down near its lower depths, 22 or so degrees below the celestial equator and not far from bottoming out at the winter solstice. Because sunlight at our mid-northern latitudes is coming in at a shallow angle, it is spread out over the landscape, and the ground and air turn cold even as we are getting slightly closer to the Sun on our somewhat elliptical orbit.

After passing full, the Moon wanes through gibbous the remainder of the week, passing north of Saturn two days later, during the afternoon of Wednesday, the 10th. That night, the lunar disk will be seen to the northeast of the ringed planet, which rises in Gemini around 6:30 PM just about half an hour before still-bright Mars transits the meridian to the south. The red planet is moving to the northeast against the background stars, and is now near the Pisces-Aquarius border. Early in the evening, look to the southwest to find brilliant Venus, the planet now setting shortly after twilight ends. It makes a lovely contrast against the fading light of the sky as night grows on. As Venus sets, Mars transits, and Saturn rises all at just about the same time. Down and to the right of Venus is Mercury, which reaches its greatest eastern elongation from the Sun on Tuesday, the 9th. In the other direction, watch for the rising of Jupiter about half an hour before midnight, the giant planet in far southern Leo not far from its border with Virgo.

This seems to be " asteroid week." Of the first four known asteroids (the set of little bodies between Mars and Jupiter), three make themselves known, as No. 3 Juno passes conjunction with the Sun on Friday, the 5th, no. 2 Pallas ceases retrograde motion on Monday the 8th, and, and no. 1 Ceres (only 590 miles, 950 km in diameter) is actually occulted by the Moon on Thursday, the 11th, though the event is visible only from the South Atlantic. The asteroids probably would have accumulated to form a real planet had Jupiter not made a mess of their orbits, and instead now sends them crashing together to grind themselves down. A few move to the inner Solar System, where upon hitting the Earth, they are known as meteorites. Speaking of which, keep your eye out in the morning for the build-up to the Geminid meteor shower, which peaks the morning of Saturday, the 14th, the Geminids the debris of Comet Phaeton (though the bright Moon will be in the way).

The stars of the Andromeda myth are at their best, the Maiden overhead in early evening, her Mother, Cassiopeia the Queen, crossing the sky to the north of the zenith, the Great Square of Pegasus now shifting to the west. Below Andromeda and Pegasus, find the sprawling figure of Pisces, and to the south of the Fishes find the tail of Cetus the Whale, marked by lonely Deneb Kaitos.
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