Sky Data
Saturday December first, sunrise is at 7:01 a.m. Eastern Standard Time. Nine hours 28 minutes later the Sun, located in the constellation Ophiuchus, sets at 4:29 p.m.
Saturday December 15th sunrise is at 7:13 a.m. and sunset occurs at 4:29 p.m.
On the last day of the month, Monday the 31st, the Sun is in Sagittarius, rising at 7:20 a.m. and setting nine hours 19 minutes later at 4:38 p.m. The altitude of the sun at the time of solar noon, its maximum daily elevation, varies during December from 27 degrees of arc on the first to 26 degrees on the 31st.
During this month average overnight temperatures recorded in Central Park drop from 37 degrees Fahrenheit on the first to 28 degrees on the last day of December.
Principal Phases of the Moon are:
| Last Quarter | December 6 at 10:31 a.m. |
| New Moon | December 13 at 3:42 a.m. |
| First Quarter | December 20 at 12:19 a.m. |
| Full Moon | December 28 at 5:21 a.m. |
Sky Cast
Mercury is in the predawn sky throughout December. It rises at 5:16 a.m. in Libra at the start of this month. On December 4th it has its greatest western elongation from the Sun, 21 degrees of arc. On the last day of 2012 Mercury is in Sagittarius, rising at 6:41 a.m.—39 minutes before the Sun.
Venus is a brilliant feature of the early morning eastern sky all month. Shining with its usual elegance, this second planet from the Sun rises at 4:37 a.m. in the constellation Libra on the first of December. It enters the predawn sky at 5:46 a.m. in Ophiuchus early on the morning of New Year’s Eve.
Mars is lingering low in our early evening southwestern sky during December. Its orbital motion is keeping approximate pace with the Sun’s eastward progression through the zodiac. On Saturday December 1st, The Red Planet is in Sagittarius and sets at 6:33 p.m. At month’s end Mars has moved into Capricornus and drops beneath the western horizon at 6:31. Discoveries on Mars by the rover Curiosity make it an especially intriguing planet this month.
Jupiter, in Taurus, is above the horizon during most of the nights in December. On the second day of the month it is at opposition, rising at sunset and setting at sunrise. At year’s end Jupiter sets at five a.m., two hours 20 minutes before the Sun rises.
During December Saturn moves from Virgo into Libra and rises progressively earlier in the predawn sky. On the first of the month the great ringed planet rises above the eastern horizon at 4:11 a.m. On the morning of the 31st it rises at 2:27 a.m.
Uranus is in the constellation Pisces. It begins the month setting at 1:30 a.m. and by month’s end sets at 11:38 p.m.
Neptune is now in Aquarius setting at 10:43 p.m. on December 1st, and at 8:48 p.m. on December 31st.
The early December opposition of Jupiter marks the highlight of this planet’s annual presentation in our night sky. It is currently in Taurus and for the next several years progresses through the most northerly constellations of the zodiac. In December, Jupiter has an altitude of about 70 degrees from the horizon when it’s at the southern meridian.
During the last week of November “Mars Fever” was rampant as the rover Curiosity, which arrived on the Red Planet in August, continued to study features at Gale crater. Hints that this remarkable rolling laboratory had made an historic discovery to be revealed at the American Geophysical Union’s fall meeting in San Francisco December 3rd, had pulses racing. What would be announced? Perhaps we’d learn of some interesting but not especially epic discovery, or maybe it would be a true game changer in our fundamental understanding of the universe—the long anticipated finding of evidence indicating some form of life native to Mars? By the time you read this you may already have an answer.
December 8-9 the brightest asteroid Vesta is at opposition in the constellation Taurus, with visual magnitude 6.4. That’s just beyond the threshold of visibility for the average person without optical aid, but it’s an easy catch with binoculars under dark skies.
The waning crescent Moon is five degrees south of Saturn on the early morning of December 10th.
The next day, Tuesday the 11th, the Moon will have moved to a position two and a half degrees directly south of Venus in the predawn sky.
At 6:45 as civil twilight begins the morning of the December 12th, a thin lunar crescent is four degrees above the southeast horizon. Then, along a sloping line to the upper right of the Moon we may see Mercury at ten degrees in altitude, Venus at 15 degrees, and Saturn 30 degrees up from the horizon.
The night of December 13-14 the Geminid meteor shower peaks with expectations of seeing over 100 events per hour at a dark sky site far from artificial lights. The best times to look are between midnight and dawn.
On the early evenings of December 14 and 15, the waxing crescent Moon is in the vicinity of Mars, which currently has visual magnitude 1.2. One hour after sunset on Friday the 14th, the Moon is eight degrees to the lower right of Mars. The same time the next evening, it is nine degrees directly above the Red Planet.
Ceres, the largest asteroid in the Solar System, is at opposition on the night of the 17-18th in the constellation Gemini. Its magnitude then is 6.7.
At the time of the Winter Solstice, 6:12 on morning of Friday December 21st the Sun is directly above the Tropic of Capricorn and winter begins in the Northern Hemisphere. At that moment the northern part of Earth's rotation axis is aimed at its maximum angular distance from the Sun’s direction and the Sun is directly above a point in the South Atlantic, about 200 miles west from the coast of Nambia. That day, we have the Sun above our horizon in New York City for just nine hours 15 minutes. This is five hours and 11 minutes less than on the first day of summer.
The evening of Monday December 24, the gibbous moon is just south of the Pleiades star cluster in Taurus.
Christmas night, the bright Moon forms a striking configuration with nearby Jupiter, the pair having a separation of less than one degree of arc during early evening.
On the night of December 28 the Full “Cold” Moon lights things up from its location in the constellation Gemini.
Sky Notes
With arrival of this year’s December solstice we also reach the much discussed date, 12/21/12, when the Mayan calendar’s current cycle concludes. Speculation has abounded for years about what, if anything, this might mean for us. Nothing in modern astronomy suggests any sort celestial or terrestrial disruption, let alone that the end of the world will occur on this date. For details about Mayan speculations you may enjoy listening to a lecture podcast from the Museum on October 10th when Hayden Planetarium Director Dr. Neil deGrasse Tyson introduced hieroglyphics expert Mark Van Stone who spoke on astronomical and cultural aspects of Mayan society:
Podcast: 2012 and the Maya: It’s Not the End of the World
Sky Lore
During December, bright stars of Orion and neighboring constellations are well placed high in the evening eastern sky. This is the most magnificent array of stars seen at any time of the year, made especially vivid due to cold, clear air so typical of many nights at this time of year. The large encompassing asterism known as the winter oval links major stellar lights of the season including Sirius in Canis Major, Rigel in Orion, Aldebaran in Taurus, Capella in Auriga, Castor and Pollux in Gemini, and Procyon in Canis Minor. These stars are features of a segment of the Milk Way called the Orion Spur, a region of active star formation.