Sky Watch: December 2013

December 1, 2013
Sky Watch

Here are the monthly sky watch highlights. Each month, we share the wonders of the universe to help you explore the night sky from your own backyard. (Note: Times listed below are ET.)

December 2013

by Bob Berman, as featured in
The Old Farmer's Almanac

Venus continues to climb higher in the west after sunset as it brightens to magnigude -4.9. its most dazzling display of the year. An easy 25 degrees high, it dangles beneath the crescent Moon on the 5th. The Moon floats above green Uranus on the 10th and is to the left of Taurus's orange star Aldebaran on the 13th.

In its fat, gibbous phase, the Moon diminishes the normally reliable Gemind meteors on the 13th and stands to the right of Jupiter on the 18th.

See our Moon Guide for December.
See our Meteor Shower Guide.

Jupiter, in Gemini, conveniently rises by 7:00 P.M. and shines at a brilliant magnitude -2.7. The Giant Planet is now a telescopic showpiece in advance of its imminent opposition on January 5.

Winter begins with the solstice at 12:11 P.M. on the 21st.

See our First Day of Winter: Solstice page.

Sky Map December 2013

by Jeff DeTray
Visit Jeff's site at

Astronomer Jeff DeTray has created the sky map below to help you navigate the November sky.

This month's highlight: Farewell to Comet ISON and a chance to see a Green Star!

Both professional and amateur sky gazers are facing the sad reality that Comet ISON did not survive its close encounter with the Sun. On November 28, Comet ISON whipped around the Sun, passing close to its surface. When the comet reappeared on the other side of the Sun, it was bright for a few hours then swiftly faded. Comet experts believe that ISON's nucleus—its small central core—was completely disrupted by its near miss with the Sun. In essence the heat, gravity, and radiation from the Sun reduced ISON to a cloud of dust and gas that rapidly dissipated. The dust cloud that was Comet ISON was soon visible only in large telescopes. The hoped-for bright naked-eye comet was not to be.

So what happened? Nothing that we didn't expect! As mentioned previously in this space, comets are among the least predictable of celestial objects. It was always possible that Comet ISON would break up as it passed close to the Sun, and that seems to be exactly what happened. So while there was a CHANCE that ISON would survive its encounter with the Sun and emerge as a bright object, no one could know for sure. So we watched, waited, and hoped for the best. In the end, Comet ISON did what comets always do—it obeyed the laws of physics.

December is a good month for bright stars. Look east on December evenings to see several of them. Among the notables is Sirius, brightest of all stars. Sirius is near the horizon in the evening during December, which may allow you to see an interesting phenomenon. The star will often seem to bounce around and to change color, turning green, red, purple, and yellow! This is because when we look at objects near the horizon, we see them through many extra miles of atmosphere. Our atmosphere is constantly moving and churning, and this causes the light from Sirius to be bent in unpredictable ways. We sometimes perceive this as rapid movement and a multi-color twinkling. In fact, the effect can be so pronounced that Sirius is frequently reported as a UFO—Unidentified Flying Object. So if you see a greenish, twinkling object near the horizon in December, it is probably not Little Green Men, but it might be the star Sirius!

In the middle of December, the Moon will be Full, and its bright glow will wash out all but the brightest stars. Compare this to the beginning and end of the month. At those times the Moon will be New, and you'll be able to see many, many more stars than you can see at Full Moon. In the constellation Gemini, the Twins, you will find the planet Jupiter, easy to see even at Full Moon. The King of Planets has been visiting Gemini for the past 6 months and will stay in that constellation until midway through 2014.

Finally, don't overlook the Pleiades star cluster, high in the sky. This compact group of stars has been used as a test of sharp eyesight since ancient times. Do you see the Pleiades as individual stars? And if so, how many can you count?

DECEMBER Sky Map: Click to View PDF

December 2013 Sky Map

Sky map produced using Chris Marriott's Skymap Pro

Explore the sky night from your own backyard. A printable black and white map is provided below!

December 2013 Sky Map PrintableClick for Printable Sky Map (PDF)
Just click, print, and bring outside!


The 2014 Old Farmer's Almanac

Leave a Comment