Northern Hemisphere gazer's guide. The sky chart is designed to correspond to the sky at 10 p.m. the first of the month, 9 a.m. in the middle of the month, and 8 p.m. at the end of the month standard time All month: For now, Jupiter remains an evening star, though reduced to only a few dark hours above the horizon. These waning weeks of its evening cycle, however, are among the most interesting. It is very bright, second only to Venus as a stellar (no pun!) attraction. It appears in the waning twilight of the southwest on December nights, less than an hour after sundown, and for a while it glimmers alone in the fading sunlight. A slender crescent moon joins the bright planet on the evening of th e 14th and 15th. Unfortunately, it doesn't move close enough to the planet to create the kind of scene that poets immortalize. Events in the calendar below occur in local time unless indicated otherwise. Dec. 1: A waning gibbous moon, up at dusk in Cancer, is virtually in line with Pollux and Castor, the twin stars of Gemini. After dark you should notice the moon drift slowly away to the left (east).
Dec. 2: Mars has been moving easterly through Virgo since October, toward the bright star Spica. It slips past Spica today and should be visible just above it before dawn this morning. The planet moves into Libra late in the month.
Dec. 3-4: The waning moon is in Leo, to the right of the star Regulus on the 3rd, to the left on the 4th. The circular group of stars above Regulus forms a backward question mark, locating the head and body of Leo.
Dec. 5: Last-quarter moon (4:01 a.m. Eastern standard time) is still in Leo, but near its hindquarters and tail (the triangle above and left of the moon). Venus passes Saturn, but they rise too late in the morning to be visible.
Dec. 6-7-8: The crescent moon rises each morning in Virgo, passing Spica and Mars on the 8th.
Dec. 8: The moon covers Mars this morning, and the occultation occurs over parts of North America. Mars disappears behind the moon's bright limb while the objects are below the horizon, but it reappears after it rises along the east coast of the United States, about 4:15 a.m. EST. The time varies slightly with location.
Dec. 9: This is the last morning to see the waning crescent moon in the sunrise glow.
Dec. 10: The moon is at perigee (nearest Earth).
Dec. 11: The moon is new at 7:54 p.m. EST, 24 hours after perigee. The close-in moon primes the spring tide, causing tomorrow's high tide to be higher and come earlier.
Dec. 14: The second-best meteor shower of the year, the Geminids, is at maximum today, with a moonless sky in the early morning hours best for viewing. You could see up to 50 meteors per hour after 1 a.m. on the 14th and 15th, but usually not as bright as the paragon of our showers, the Perseids.
Dec. 13-16: Chances of seeing the new crescent moon are poor on the 13th, good on the 14th. It appears higher in the evening twilight nightly and stays up later, below Jupiter, until the 15th, then higher than the planet.
Dec. 16: Too bad we can't see Mercury pass Saturn in the morning sky only a moon's diameter away. Mercury is at its greatest westerly elongation (to the sun's right), actually brighter than Saturn. But celestial geometry is against us: The planets rise too late to make an appearance.
Dec. 18: First-quarter moon (8:58 p.m. EST) is in Pisces, near the vernal equinox. The eastern edge of the Square of Pegasus is just above the moon, and its two stars point downward, very close to the vernal equinox.
Dec. 21: The sun reaches the winter solstice, in Sagittarius along the ecliptic (the sun's apparent path through the stars) 231/2 degrees south of the equatorial plane, at 5:08 p.m. EST, and the winter season begins in the Northern Hemisphere. Earliest sunset occurred on Dec. 8, however, and the latest sunrise will be on Jan. 6.
Dec. 22: The Ursid (named for Ursa Major) meteor shower is at maximum, with no moon in the morning. Not very productive (15 meteors per hour), but maybe it will be a warm morning.
Dec. 23-25: Taurus acts as host to a fattening gibbous moon, moving out of Aries on the 23rd, close to the Pleiades, passing the Hyades and Aldebaran on the 24th and nestling between the Bull's horns on the 25th.
Dec. 24: Jupiter makes a handsome Christmas star, low in the southwest at dusk. All that moonlight won't bother Jupiter, but it does add to the problems of finding Halley's comet, a dim, fuzzy object without much of a tail yet, above Jupiter in Aquarius, just about on the equatorial plane.
Dec. 27: Full moon (at 4:01 a.m. EST) is in Gemini, above the stars Pollux and Castor. Tomorrow night at the same hour it rises with the twins, just about where it was at the beginning of December.
Dec. 30-31: The moon is back in Leo again, riding up the eastern sky with the Lion in the late evening.