December Skies 2006

December’s skies bring several remarkable sights.  Long nights combine with Winter’s prominent stars and constellations for convenient evening and pre-dawn viewing.

Three quite spectacular events to watch this month are:
• A rare 3-planet conjunction in the dawn sky between December 8th and 13th
• A 2-planet conjunction in the dawn sky with the Moon on the morning of December 18th
• The Geminid Meteor Shower, overnights from December 10th through the 14th. This is usually Arizona’s finest meteor shower of the year.

With the upcoming holidays, December is also an excellent time to plan to give (or treat oneself to) a quality pair of binoculars to help navigate the night sky!

The Sun:  The Sun begins December in the constellation of OPHIUCHUS, and remains there until December 18th, when it enters SAGITTARIUS.  Winter officially begins on December 20th, the day of the Winter Solstice, when Sun is lowest in the sky at noon for the entire year.

The Moon:
December’s FULL MOON occurs on the afternoon of the 4th in TAURUS.
The 3rd QUARTER Moon occurs on the morning of the 12th in LEO.
NEW MOON is on the 20th in SAGITTARIUS.
The 1st QUARTER MOON occurs on December 27th in PISCES.

In December the Moon passes all five naked-eye Planets:
SATURN: VERY near the Moon (moonrise is at 10p.m.) overnight the 9th – 10th.
JUPITER, MARS & MERCURY: near the VERY thin crescent Moon in SCORPIO in the dawn sky the morning of the 18th.
VENUS: South (left) of the VERY thin crescent Moon in Sagittarius the evening of the 21st.

The Moon can be seen near these Bright Stars:
Waning gibbous Moon near Castor & Pollux in Gemini the evening of the 7th.
Waning gibbous Moon near Regulus in Leo the mornings of the 10th and 11th.
Waning crescent Moon very near Spica in Virgo the morning of the 15th.
Waxing gibbous Moon passes through (occults) stars in the Pleiades (“7 Sisters”) star cluster before dawn the morning of the 31st.

The Evening Sky:
The Sun: :  December’s earliest sunsets of the year occur at about 5:15p.m. throughout the first half of the month. By month end, sunset still occurs only 10 minutes later (at 5:25p.m.)!

Evening Planets: VENUS and SATURN.
Venus, the brightest night sky object after the Moon, begins the month very close to the Sun low in the West after sunset in OPHIUCHUS. Venus moves into Sagittarius on the 7th, where it remains the rest of December. Since Venus is on the far side of the Sun from the Earth, it appears through a telescope as a brilliant white, but very small, disk at near “Full” phase. As Venus continues to catch up with the Earth in its orbit of the Sun, Venus will move farther from the Sun in the evening sky and become easier to observe. Although Venus can now be glimpsed with binoculars just after sunset, it will become progressively more visible in January.

Saturn is found in LEO all month. It rises just before 11p.m. on the 1st but 2 hours earlier at 8:50p.m. at month end.  Telescopic observers will easily notice Saturn’s prominent ring system and some of its brighter moons.

Geminid Meteor Shower:  During December, Arizonans are treated to our best meteor shower, the Geminids.  The shower is best observed over the nights of the 12th 13th and the 13th – 14th.

Visit this page to view our separate page detailing this spectacular event.

If you are able to photograph a Geminid meteor, send it by email to info@evliving.com.  Next month we will publish Geminid meteor photos sent in by our evliving.com astronomy readers!

The Morning Sky
The Sun:  Sunrise in Central Arizona occurs about 7:15a.m. on December 1st, but as late as 7:35a.m. on the 31st.  Our early sunsets and late sunrises make December’s days the shortest of the year.

The Moon: The waning MOON is best seen in the morning sky between the 8th and the 18th of December. The waxing Moon will again be high in the morning sky between the 29th and 31st.

Morning Planets: MERCURY, JUPITER & MARS.
Mercury begins the month in LIBRA as it moves toward the Sun in the dawn sky. However, it will be easy to spot through binoculars.  Scan the Southeastern sky about 1 hour before sunrise to spot the elusive and speedy orange planet.  On December 9th, Mercury moves Eastward into Scorpio on the 14th, and on into Ophiuchus on December 13th.  It rises more than an hour before the Sun from the 1st through the 14th of the month, but should still be visible for a few mornings later, again with binoculars.  From the 8th through the 13th, Mercury will be quite close to JUPITER and MARS, as Mercury passes both of those planets heading sunward. These 3 planets will not meet again until 2009!

Mars in December is slowly approaching the Earth enroute to a close encounter next December, and is gradually growing larger in apparent size. Small telescopes will show the planet as a round orange disk.  Mars begins December in LIBRA, moves into SCORPIO on December 6th, and then into OPHIUCHUS on December 16th, where it remains for the rest of the month. From the 8th through the 13th, Mars will be quite close to both MERCURY and JUPITER.  MARS passes very close to Jupiter on the morning of the 11th, then lags behind giant Jupiter.

On the morning of December 18th, the “old” waning crescent Moon hangs South (right) of Mars and Jupiter. The Moon and Jupiter rise at 5:49a.m., while Mars rises at 6:10a.m. Sunrise is more than an hour later, so watch these 3 objects for the few minutes they are visible together.

Jupiter also starts December in LIBRA and moves Eastward into SCORPIO on the 5th, and then moves farther East into OPHIUCHUS on the 28th.  Jupiter is rapidly moving away from the Sun and rising earlier each day, rising at about 6:40a.m. on the 1st of December and at about 5:10a.m. on the 31st.  Jupiter is still too near the Sun and too low in the dawn for telescopic observers to watch Jupiter’s magnificent cloud bands and four bright moons orbiting the planet.

Between December 7th and 10th Jupiter passes quite close to the 2nd magnitude star Beta Scorpii.  Jupiter then passes close to Mercury on the 10th and 11th, and immediately passes Mars from the 11th through the 13th.  These spectacular conjunctions can be enjoyed with the naked eye or binoculars, but don’t miss this show!

(To repeat, be sure to watch the conjunction of the crescent Moon, Jupiter and Mars on the morning of December 18th!  The thin Moon will be South (right) of Jupiter, while Mars is a bit lower in the sky that morning.  The next such grouping of Jupiter, Mars and the Moon will not occur until February, 2009!

What Else to See?  Observers with binoculars or small telescopes may view the Moon occult (pass in front of) or graze (pass very near to) several stars of 6th magnitude or brighter between December 9th and 30th. A listing of these events may be found here.

December is the first month for convenient early morning viewing of the Spring stars and constellations. Soon the “Summer Triangle” Milky Way constellations of CYGNUS, LYRA, and AQUILA will again be visible before dawn in the Northeast.  These stars are so far North in the Arizona sky that in December and January they are visible both after sunset and before dawn.

Binoculars or a small telescope will add to the pleasure of viewing the many prominent Winter sky objects.  Be sure to check out Saturn, the Pleiades star cluster in Taurus, and the Orion Nebula (in the center of Orion’s sword).

Good Luck Observing!