This Week's Sky at a Glance
Some night sky sights for December 20 28
To find all such events for every time zone worldwide, see "Action at Jupiter" in the December Sky & Telescope, pages 51 and 52.
Saturday, December 21
Sunday, December 22
Monday, December 23
Tuesday, December 24
Wednesday, December 25
Thursday, December 26
Friday, December 27
Saturday, December 28
Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and once you know your way around, the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.
You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.
Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability, which means heavy and expensive). As Terence Dickinson and Alan Dyer say in their invaluable Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."
This Week's Planet Roundup
Venus (magnitude –4.8) shines brightly in the southwest during dusk. It's moving lower rapidly now, as it wanes to a thinner crescent: from 14% sunlit on December 20th to just 7% lit on the 27th. During this time the crescent enlarges from 51 to 57 arcseconds from horn to horn. The best time to observe it in a telescope is late afternoon, before sunset. Here's our article See Venus's Thin Crescent.
Mars (magnitude 1.0, in the head of Virgo) rises around midnight or 1 a.m. By dawn it's at its highest in the south, but in a telescope Mars is still very small, only 6.4 arcseconds in diameter. Can you see its gibbous shape?
Jupiter (magnitude –2.7, in Gemini) rises in the east-northeast around the end of twilight, with Pollux and Castor to its left. It blazes highest around 1 a.m. In a telescope Jupiter has grown to a big 46 or 47 arcseconds wide as it nears its January 5th opposition. Read all about observing Jupiter in the January 2014 Sky & Telescope.
Saturn (magnitude +0.6, in Libra) is well up in the southeast as dawn begins to brighten. Look for it far to the lower left of Mars and Spica, and far below brighter Arcturus.
Uranus (magnitude 5.8, in Pisces) is high in the south right after dark.
Neptune (magnitude 7.9, in Aquarius) is moving lower in the southwest now after dark. Finder charts for Uranus and Neptune.
All descriptions that relate to your horizon including the words up, down, right, and left are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.
Eastern Standard Time (EST) is Universal Time (UT, UTC, or GMT) minus 5 hours.
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