Sky Calendar: Observing Events for December 2010

The SkyCalendar is provided by StarryNight Education with contributions by Larry Sessions andGeoff Gaherty.

Moon Phases

Sun.,December 5

New Moon,10:29 p.m.

TheMoon is not visible on the date of New Moon because it is too close to the Sun,but can be seen low in the east as a narrow crescent the morning before, justbefore sunrise. It is visible in the low southwest the evening after New Moon.

Mon.,December 13

FirstQuarter Moon, 8:59 a.m.

TheFirst Quarter Moon rises around noon, and sets around 1 a.m.

Tue.,December 21

Full Moon,3:13 a.m.

TheFull Moon of December is usually known as the Oak Moon. In Algonquian it iscalled Cold Moon. Other names are Frost Moon, Long Night?s Moon and Moon BeforeYule. In Hindi it is known as Margashirsha Poornima. Its Sinhala (Buddhist)name is Unduvap Poya. The Full Moon rises around sunset and sets aroundsunrise, the only night in the month when the Moon is in the sky all nightlong. The rest of the month, the Moon spends at least some time in the daytimesky.

Mon.,December 27

LastQuarter Moon, 11:18 p.m.

TheLast or Third Quarter Moon rises around midnight and sets around 11 p.m. It ismost easily seen just after sunrise in the southern sky.

ObservingHighlights

Sat.,December 4, dawn

Venusgreatest illuminated extent

Thismorning Venus will be at its most brilliant, exposing the largest area ofsunlit clouds of the current apparition. Two things are going on. Theilluminated crescent of Venus is getting larger, percentage wise, as the planetmoves towards full sunshine. At the same time, Venus is receding from theEarth, and so getting smaller in diameter. On this date the two balance out,giving Venus its greatest illuminated extent, and making it appear at itsbrightest, magnitude ?4.9.

Tue.,December 14, midnight to dawn

GeminidMeteor Shower peaks

Theradiant of the Geminid meteor shower, close to Castor in Gemini, is above thehorizon all night. The peak of the shower is at 6 a.m. Tuesday morning. Thenumber of meteors observed always increases after midnight because Earth isheading into the meteoroid stream, so the best views will be from midnight todawn. This is one of the best meteor showers in the year, worth braving thecold to watch.

Mon./Tue.,December 20/21

Total LunarEclipse

Thefirst hint of the shadow of the Earth falling on the Moon occurs at 29 minutespast midnight EST (9:29 p.m. PST). The umbra, the darkest part of the Earth?sshadow, begins to encroach on the Moon at 1:32 a.m. EST/10:32 p.m. PST. Maximumeclipse is at 3:17 a.m. EST/12:17 a.m. PST. The umbra leaves the Moon at 5:01a.m. EST/2:01 a.m. PST, and the eclipse ends at 6:05 a.m. EST/3:05 a.m. PST.

Planets

Mercury will be an ?eveningstar? at the very beginning of the month, but will be too close to the Sun toobserve for the rest of the month. This is an unfavorable apparition forobservers in the northern hemisphere, but a good one for southerners.

Venus? is a brilliant?morning star? all month. It reaches greatest brilliancy on December 4.

Mars is pretty much lostin evening twilight, on the far side of the Sun.

Jupiter is well placed allevening, dominating the southern sky. It is in the constellation Aquarius forthe first half of the month, moving into Pisces on December 17. It sets aroundmidnight.

Saturn is now a morning?star? in Virgo. Its rings have returned to their usual glory after being onedge for the last two years.

Uranusisin Pisces all month, and remains within a few degrees of Jupiter.

Neptune is in Capricornusand sets around 10 p.m.

The SkyCalendar is provided by StarryNight Education, the leader in space science curriculum solutions.

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