Monday, December 19
Mars continues to put on a nice show these December evenings. It appears about 30° above the southwestern horizon once twilight fades to darkness, and it doesn’t set until after 9 p.m. local time. The magnitude 0.8 Red Planet currently lies among the background stars of Aquarius. A telescope shows the world’s 6"-diameter disk, though you’ll be hard-pressed to see any surface detail except under exceptional viewing conditions.
Tuesday, December 20
Last Quarter Moon occurs at 8:56 p.m. EST. The Moon doesn’t rise until a few minutes after midnight, however, by which time it will appear almost imperceptibly less than half-lit. The Moon spends the morning hours among the background stars of western Virgo.
Wednesday, December 21
The Ursid meteor shower peaks tonight. The shower’s radiant — the point from which the meteors appear to originate — lies in the constellation Ursa Minor, near the Little Dipper’s bowl. The radiant is visible in the north all night, but it climbs higher as dawn approaches. The waning crescent Moon won’t interfere much after it rises around 1 a.m. local time tomorrow morning, though your best views likely will come between 11 p.m. and 1 a.m. Observers with clear skies should be able to see 5 to 10 Ursid meteors per hour.
Earth’s winter solstice occurs at 5:44 a.m. EST. At that moment, the Sun reaches its farthest point south in the sky. The solstice marks the official beginning of winter in the Northern Hemisphere, and tonight has more hours of darkness than any other. From mid-northern latitudes, however, the earliest sunset occurred about two weeks ago and the latest sunrise won’t happen until early January.
Thursday, December 22
The waning crescent Moon appears just above Jupiter in this morning’s sky. The planet rises about a half-hour after our satellite, and both are clear of the horizon by 2 a.m. local time. They remain conspicuous until twilight is well underway. If you look carefully, you also should see the 1st-magnitude star Spica in their vicinity. Virgo the Maiden’s luminary lies about the same distance below Jupiter as the Moon stands above it.