Skylights featured on Astronomy Picture of the Day

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Skylights featured six times on Earth Science Picture of the Day:
1 , 2 , 3 , 4 , 5 , 6

Comet Holmes

Photo of the Week. Here comes Comet Holmes. The picture is centered on Mirfak, Alpha Persei (the brightest star of Perseus). The comet, seen the night of October 31, 2007, is the bright "star" down and a bit to the left of Mirfak (near the lower edge of the picture). Holmes is here near its brightest following its late October outburst, and is beginning to show some fuzzy structure.

Astronomy news for the week starting Friday, December 28, 2007.

Happy New Year to all and best wishes for a great 2008.

As always, we begin with the ever-shifting Moon, which celebrates the coming end of 2007 by passing through third quarter the night of Sunday, December 30th. The pair of days before that event, the Moon will be in its last waning gibbous phase, while the New Year begins with the Moon in the waning crescent. The week concludes with the Moon passing through apogee (actually on Wednesday, January 2), where it is farthest from Earth.

As the year begins, Mars now rises at the Gemini-Taurus border just before sunset, gloriously transiting the meridian just after 11 PM. Mid-evening sees Saturn, still in Leo, rising at 9:30, then transiting at 4 AM, half an hour before Venus rises in the southeast.

The Big Event is the passage of the Earth through its perihelion point the evening of Wednesday, January 2, at 6 PM Central Time. At that time it will be closest in its orbital path to the Sun, a distance of 0.983 Astronomical Units (the average Earth-Sun distance), or 147 million kilometers, 91.4 million miles (98.3 percent closer than average). That perihelion takes place in the dead of northern winter clearly shows that the distance between the Earth and Sun has little if any effect on the seasons, which are caused by the 23.4 degree tilt of the Earth's rotation axis relative to its orbital axis. The seven percent variation in solar heating between perihelion in January and aphelion (farthest from the Sun) in July is quite lost in the distribution of Earth's oceans and land masses. The closeness of perihelion passage to New Year's Day is pure coincidence.

The other Big Event (there are two) is one of the best meteor showers of the year, the Quadrantids (named after the defunct constellation Quadrans, the Quadrant, just to the east of the Big Dipper), which peaks the night of Thursday, January 3 - the morning of Friday, January 4, when you might see up to 100 meteors per hour, the crescent Moon not much of a hindrance. The best time is predicted to be 12:40 AM CST.

As the New Year progresses, the autumnal stars of the Perseus Myth begin to move into the western evening skies. Look for Perseus himself nearly overhead between 8 and 9 PM. To the west lies Cassiopeia, the Queen, while farther over is the dim pentagon that makes her husband, Cepheus, the King.
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