Thursday, December 1, 2011

December 2011 Sky Events

Moon Phases

Fri., December 2, 4:52 a.m. EST

First Quarter Moon

The First Quarter Moon rises around 1 p.m., and sets around 1 a.m.

Sat., December 10, 9:36 a.m. EST

Full Moon

The Full Moon of December is usually called the Oak Moon. In Algonquian it is called Cold Moon. Other names are Frost Moon, Winter Moon, Long Night’s Moon, and Moon Before Yule. In Hindi it is known as Margashirsha Poornima. Its Sinhala (Buddhist) name is Unduvap Poya. The Full Moon rises around sunset and sets around sunrise, the only night in the month when the Moon is in the sky all night long. The rest of the month, the Moon spends at least some time in the daytime sky.

Sat., December 17, 7:48 p.m. EST

Last Quarter Moon

The Last or Third Quarter Moon rises around 11 p.m. and sets around noon. It is most easily seen just after sunrise in the southern sky.

Sat., December 24, 1:06 p.m. EST

New Moon

The Moon 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 a morning or two before, just before sunrise. It is visible low in the west an evening or two after New Moon.

Observing Highlights

Sat., December 10, dawn

Total Lunar Eclipse

This eclipse will be seen in its entirety in eastern Asia, Australia, Oceania, and Alaska. The Moon will rise eclipsed in the early evening in Europe and Africa, and set eclipsed just before dawn in western North America. The graphic shows how it will look just before dawn in central California, surrounded by first magnitude stars.

Thu., December 22, 12:30 a.m. EST


Winter solstice in the northern hemisphere, summer solstice in the southern hemisphere. The Sun is at its farthest southern declination, and is 6.5 degrees away from the center of the Milky Way. This is exactly the same “alignment” as will occur on December 21 2012, yet no catastrophes have been predicted for this year, just as none will occur next year. Because of the extreme difference in brightness between the Sun and the Milky Way, this “alignment” is observable only in a computer simulation.

Thu., December 22, and Fri., December 23, dawn

Close encounter between Mercury and the Moon

The Moon will be just to the right of Mercury on the Dec. 22 (shown here) and just to the left of Mercury on the Dec. 23.

Tue., December 27, 10:52 p.m. EST

Jupiter satellite show

Three of Jupiter’s moons will put on a fine show tonight. Callisto will be in an unusual position due south of the planet because of the extreme tilt of the plane of Jupiter’s moons this year. Europa will be moving off from in front of Jupiter on one limb while its shadow begins a transit on the opposite limb. Ganymede, well off to the right, will still be casting its shadow just below Europa. Finally, the Great Red Spot will be perfectly placed right in the middle of all this.


Mercury is well placed in the eastern sky before sunrise for the last half of the month.

Venus is low in the evening sky after sunset all month. The waxing crescent Moon will pass close to Venus on Mon. Dec. 26 and Tue. Dec. 27.

Mars spends all of December in the morning sky in Leo. It now outshines nearby Regulus and grows from 7 arc seconds to 9 arc seconds during the month, large enough to reveal its polar cap and dark surface markings in a 6-inch (150-mm) telescope. It is now approaching magnitude 0, one of the brightest objects in the morning sky.

Jupiter continues to be well placed in the evening sky all month on the border between Aries and Pisces. Jupiter and Venus are the brightest objects in the night sky other than the Moon.

Saturn is visible before dawn in the eastern sky. It now shines brighter than nearby Spica.

Uranus is well placed in the early evening in Pisces all month.

Neptune is well placed in the early evening in Aquarius all month.

Geoff Gaherty
Starry Night Software Support