Monday, December 5
This is a good week to target the dwarf planet Ceres, the largest object in the asteroid belt between the orbits of Mars and Jupiter. It lies among the background stars of northern Cetus and appears more than halfway to the zenith in the southern sky during early evening. To find it, first locate magnitude 3.6 Theta (q) Ceti, then head 8° north to the magnitude 5.6 star 42 Ceti. Eighth-magnitude Ceres lies 3° east of 42 Ceti all week.
Tuesday, December 6
Brilliant Venus passes 0.8° south of the 9th-magnitude globular star cluster M75 this evening. Use large binoculars or a telescope with a low-power eyepiece to get the best view of this conjunction. The two objects reside in far eastern Sagittarius, though the planet will cross into neighboring Capricornus by tomorrow evening.
Wednesday, December 7
First Quarter Moon occurs at 4:03 a.m. EST. The Moon doesn’t rise until shortly after noon local time, however, and by the time darkness sets in, our satellite appears 57 percent illuminated. It then lies in northeastern Aquarius, some 25° below the Great Square of Pegasus.
Although people in the Northern Hemisphere won’t experience the shortest day of the year for another two weeks (at the winter solstice December 21), those at 40° north latitude will see the Sun set earlier today than at any other time this year. Tomorrow’s sunset will arrive about two seconds later and, by the solstice, our star will set three to four minutes later than today. The date of earliest sunset depends on latitude — the farther north you live, the closer it occurs to the solstice.
Thursday, December 8
The Geminid meteor shower gets underway this week. Although the shower doesn’t peak until the night of December 13/14, you may get a better view now because the Full Moon will share the sky on the peak night. For the best views, observe after the waxing gibbous Moon sets — around 12:30 a.m. local time this morning and about 70 minutes later each successive day — and before twilight begins around 5:30 a.m. To tell a Geminid meteor from a random dust particle burning up in Earth’s atmosphere, trace the streak of light’s path backward. A shower meteor will appear to originate from the constellation Gemini the Twins.