Indiana University Bloomington

Star Trak: December 2013

  • Dec. 2, 2013

FOR IMMEDIATE RELEASE

BLOOMINGTON, Ind. -- Venus will blaze low in the southwest as the evening sky darkens in early December, becoming as bright as it ever gets. If you have fresh snow, wave your hand a foot above the ground under a dark sky and see the shadow cast on the snow by Venus.

At the beginning of the month, Venus will set two hours after the sun for observers at 40 degrees north latitude, though it will be only 15 degrees above the horizon at sunset. It will still be almost as high on Dec. 22. But by New Year’s Eve, a much dimmer Venus will be just 4 degrees above the horizon and will set less than an hour and a half after the sun.

Jupiter will rise around 8 p.m. local time as December starts, but it will be visible in bright twilight less than a half hour after sunset at month’s end. By late evening it will dominate the eastern sky. It will reach opposition (opposite the sun in our sky) next month.

Mars will rise around 1 a.m. local time in early December and an hour earlier by the end of the month. The red-orange planet will be highest during morning twilight for telescopic observations.

Saturn will rise about 5 a.m. local time as December begins and an hour and a half earlier as it ends. Even in morning twilight it will be rather low in the southeast, but this month its rings will open to 21 degrees from edgewise.

At the start of the month, Mercury will still be visible at dawn to the lower left of Saturn, but it will appear lower each morning and soon disappear from view. Mercury will reach superior conjunction with the sun on Dec. 29.

Meteor showers

The annual Geminid meteor shower, which will reach its maximum on the night of Dec. 13-14, usually offers the best show of the year, outperforming even the Perseid shower of August. But this year the moon will be almost full when the Geminids peak. It won’t set until about 4 a.m. local time, an hour before the start of morning twilight, so there will be a brief window of moonless sky for watching meteors.

In a clear dark sky, observers may see more than 50 meteors per hour. The nights before and after the peak should also provide good viewing opportunities. These "shooting stars" will seem to come from a point near the bright stars Castor and Pollux in the constellation Gemini the Twins, which gives the shower its name.

Solstice

The sun will be farthest south in Earth's sky at 12:11 p.m. EST (17:11 Universal Time) on Dec. 21, marking the start of winter in the Northern Hemisphere and summer in the Southern Hemisphere. For the next six months in the Northern Hemisphere, the days will be getting longer.

Moon phases

The moon will be new on Dec. 2, at first quarter on Dec. 9, full on Dec. 17 and at third quarter on Dec. 25.

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Hal Kibbey

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  • hkibbey@indiana.edu