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 .


Photo of the Week.. A glorious sunset lights the western sky.

Astronomy news for the week starting Friday, January 31, 2003.

Welcome to February, the month just before March, when spring will begin. And Happy (after the fact) Groundhog Day, an astronomical holiday that falls halfway between the first day of winter and the first day of spring.

The week begins with the Moon in its smallest crescent phase as it prepares to pass new on Saturday, February 1. Were this a normal month with 30 or 31 days, we would experience a sort of "anti-blue-moon" with two new moons during the month, but because February is a bit shorter than the lunar phase period of 29.5 days, the next one will be on March 2. The first glimpse of the crescent can be had the night of Sunday, February 2nd. Then watch during the week as the waxing moon climbs out of western evening twilight, getting higher each night as the sky darkens, the nighttime side of the lunar disk awash with Earthlight.

Planetary extremes make the news. The smallest of the naked-eye planets, Mercury, reaches its greatest western elongation on Monday the 3rd, when it will be 25 degrees to the west of the Sun and visible in the morning dawn sky. Given the flatness of the ecliptic and Zodiac against the eastern morning horizon this time of year, the apparition is not particularly good, but you might still see the bright little one low in the east-southeast in twilight. If you cannot find it, you can at least admire brilliant Venus high to the southeast with fainter reddish Mars to the west of it. Two days before, on Sunday the 2nd, the Solar System's giant, Jupiter, passes opposition with the Sun. Now moving retrograde, or to the west, through Cancer, Jupiter will on that date rise at sunset, set at sunrise, and cross the meridian to the south at midnight, making it the best time of the year for viewing. The planet is magnificent to see through even a small telescope with its cloud belts and the changing patterns made by its four "Galilean" moons, Io, Europa, Ganymede, and Callisto. While examining Jupiter, do not forget glorious Saturn, which rides the sky in eastern Taurus some 60 degrees to the west of Jupiter, the telescopic view even better, as the rings are fully wide open.

In the northern sky, the "W" of Cassiopeia is moving out, circling the pole into the northwest, while being replaced by the wonderful sight of the Big Dipper in the northeast, the classic figure standing on its handle. To the east of Cassiopeia find the star streams that make the hero Perseus. If you have access to a dark sky, you can see the flow of a glorious part of the Milky Way running through Perseus and Cassiopeia, the band of stars then lost into the northwest. Looking back to the Dipper, note the second star in from the end of the handle, which actually consists of a pair of stars, Mizar and Alcor, a naked-eye double that the ancient Arabians called the "horse and rider."
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