Friday, December 21
Saturday, December 22
Sunday, December 23
And at 10:45 p.m. EST, Jupiter's Great Red Spot should cross the planet's central meridian.
For all of Jupiter's satellite events and all the Great Red Spot's transit times, get our new JupiterMoons app.
Monday, December 24
Tuesday, December 25
Wednesday, December 26
Thursday, December 27
Friday, December 28
Saturday, December 29
Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
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 the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope effectively.
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 certainly not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability). 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 –0.5) can be spotted during dawn, well to the lower left of brilliant Venus low in the southeast. They're 8° or 9° apart.
Venus (magnitude –3.9) is still the bright "Morning Star," but it's moving lower in the dawn every week. Look southeast.
Mars (magnitude +1.2) still remains low in the southwest in evening twilight. In a telescope it's just a tiny blob 4.3 arcseconds in diameter — hardly larger than Uranus!
Jupiter (magnitude –2.8, in Taurus) is up and glaring in the east as twilight fades. It climbs to dominate the high eastern and southeastern sky in the evening, with orange Aldebaran 5° below it and the Pleiades twice as far to its upper right. Jupiter is highest in the south around 10 p.m. local time. In a telescope it's still a big 47 arcseconds wide.
Saturn (magnitude +0.7, in Libra) rises in the east-southeast around 3 a.m. local time. By the beginning of dawn it's fairly high in the southeast, far upper right of Venus. That's the best time to get your telescope on it. Saturn's rings are now tilted 19° to our line of sight, the widest open they've been in seven years.
Uranus (magnitude 5.8, in Pisces) and Neptune (7.9, in Aquarius) are the south and southwest, respectively, right 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) equals Universal Time (also known as UT, UTC, or GMT) minus 5 hours.
Like This Week's Sky at a Glance? Watch our SkyWeek TV short. It's also playing on PBS!
To be sure to get the current Sky at a Glance, bookmark this URL:
If pictures fail to load, refresh the page. If they still fail to load, change the 1 at the end of the URL to any other character and try again.