SKYLIGHTS

Astronomy news for the week starting Friday, December 15, 2000.

The Moon descends during the very early part of the week through the tail end of its waning gibbous phase. Now rising well after sunset, it then passes through third quarter the night of Sunday the 17th, the phase actually reached a few hours before near- midnight moonrise in North America. As the lunar crescent wanes, it will pass above Mars the night of Tuesday the 19th, and by moonrise will be seen somewhat to the northeast of the red planet. Mars, now in Virgo, just to the northeast of the star Spica, is slowly brightening as the Earth (moving slightly faster around the Sun) creeps up on it, and is now just making the transition from second magnitude to first. Best visibility, Mars opposite the Sun, is still six months off, however. For planets we have instead the glorious evening view of brilliant Venus in the southwest in Capricornus, and Jupiter and Saturn, hosted by Taurus, climbing the eastern sky.

The big event this week involves our own planet Earth, which sees the Sun pass the Winter Solstice in Sagittarius at 7:37 AM Central Standard Time (8:37 EST, 5:37 PST). At roughly the time of sunrise, the Sun will have reached its lowest point for the year, 23 degrees 26 minutes south of the celestial equator, and astronomical winter will begin in the northern hemisphere. The northern end of the Earth's axis will be tilted as far as possible away from the Sun, sunlight must spread itself out over a larger area, and the northern hemisphere will receive its minimum solar heat. Since it takes some time for the Sun to climb back up north, the weather, as we all know, will continue to chill. The southern hemisphere, however, now glories in sunlight, with the Sun passing overhead at the Tropic of Capricorn, the parallel of latitude that lies 23 degrees 26 minutes south of the equator. As part of the whole event, the Sun will not rise north of the Arctic Circle, and will not set south of the Antarctic Circle (these located 23 degrees 26 minutes from the north and south poles of the Earth).

Winter: with the constellations of autumn starting to make their transition to the west, the Great Square of Pegasus high to the south at 7 PM, Orion and his mighty crew begin to make an impact in the evening sky, the celestial hunter hitting the meridian to the south around midnight. Here we can glory in the "winter-six" of Orion, his two hunting dogs Canis Major and Canis Minor, Gemini (its Summer Solstice now high in the sky), Auriga, and Taurus, the latter carrying the Hyades, the Pleiades, Jupiter, and Saturn to the west.