This Week's Sky at a Glance
Some night sky sights for December 6 14
Read the tale of the death of Comet ISON. Sigh. This might have been the week when it was at its best.
Saturday, Dec. 7
The reason? Local Apparent Solar Time is shifting with respect to Local Mean Time during this part of the year, an effect caused by the tilt of Earth's axis and the ellipticity of Earth's orbit. Be glad that we use standard time, so you don't have to keep adjusting your clocks to the inconstant Sun like in olden days. Standard time made things simpler for society but complicated things for skywatchers.
Sunday, December 8
Monday, December 9
Tuesday, December 10
Wednesday, December 11
Thursday, December 12
Saturday, December 14
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).
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
Mercury (magnitude –0.7) is sinking away deep into the glow of sunrise.
Venus (magnitude –4.9) is the brilliant "Evening Star" in the southwest during and after dusk. It's shining at its brightest for the year, and it doesn't set until more than an hour after dark. In a telescope, Venus has waned to a crescent about 25% lit and has enlarged to about 42 arcseconds tall, as it swings toward us around the Sun.
Mars (magnitude 1.2, in the head of Virgo) rises around 1 a.m. By dawn it's very high in the south. In a telescope Mars is still tiny and gibbous, 5.8 arcseconds wide.
Saturn (magnitude +0.6, in Libra) is low in the southeast as dawn begins to brighten. Look for it then far to the lower left of Mars and Spica, and far lower right of brighter Arcturus.
Uranus (magnitude 5.8, in Pisces) and Neptune (magnitude 7.9, in Aquarius) are still well placed in the southern sky shortly 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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