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December 2013: sounding the depths: as bright winter stars emerge in the east, dimmer, deeper sights await your telescope.

IN DECEMBER the eastern sky comes alive with brilliant stars that promise a "stellar" new year. Turn the map on the facing page so its "Facing East" horizon is level at the bottom. Orion, Taurus, Perseus, Auriga, Gemini ... there's a lot going on here!

For one thing, no time of year offers so many big star clusters. Grandest are the tight, bright Pleiades and the big, loose Hyades, both in Taurus. The Pleiades now float above the Hyades in the east, as the map shows.

You can see several other star clusters with your unaided eye if your sky is relatively free of light pollution. The Double Cluster in Perseus looks like a dim, elongated bit of Milky Way; look for it plotted between Perseus and Cassiopeia, very high in the northeast. A small telescope turns the Double Cluster into a pair of sparkling swarms.

Binoculars convert the dim naked-eye stars around Alpha (a) Persei into a bright, sprawling array: the Alpha Persei Association, a swarm of moderately young stars that were born together and are now drifting apart. A fine cluster for low magnification in a telescope is much smaller M34, between Perseus and the bright foot of Andromeda. See the photo above.

M34 lies near one of the most famous variable stars: Beta ([beta]) Persei, better known as Algol. Another well-known variable is in the southeast in Cetus: Omicron (o) Ceti, better known as Mira. And be sure to check in on the classic Cepheid variable we mentioned last month, Delta ([delta]) Cephei, now high in the northwest.

To find the brightest galaxy at the time of our map, scrutinize its location just about straight up. You're looking for M31, the Great Galaxy in Andromeda, just off Andromeda's knee. In a dark sky it's a very dim, elongated blur to the naked eye. Binoculars or a telescope show its luminous central hub even through a fair amount of light pollution--but don't expect to see any spiral detail.

Planets in December 2013

Mercury (about magnitude -0.7) is still in view low in bright dawn during early December, but it becomes lower and harder to see every day. Look for it just above the east-southeast horizon, below Saturn and a little left.

Venus (about magnitude -4.8) begins the month well up in the southwest during evening twilight, but it moves lower at dusk throughout December--slowly at first, then faster.

Mars (about magnitude +1.0, in Virgo) rises around midnight or 1 a.m. It's highest in the south around the beginning of dawn. In a telescope Mars is still disappointingly tiny, a mere 6 or 7 arcseconds wide.

Jupiter (magnitude -2.6, in Gemini) rises in twilight or shortly after and dominates the eastern sky with its outstanding brilliance for the rest of the evening.

Saturn (magnitude +0.6, in Libra) has emerged into good dawn view. Look for it moderately well up in the southeast before the sky grows too bright.

The Geminid meteor shower, often the richest of the year, should peak on the night of December 13-14. But this year the bright light of the waxing gibbous Moon will interfere. With luck you might see up to a meteor per minute from 9 or 10 p.m. until dawn.

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Publication:SkyWatch
Date:Jan 1, 2013
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Previous Article:November: King and Queen of the North: Dim Cepheus and bright Cassiopeia swing high above the north celestial pole.
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