This Week's Sky at a Glance
Some night sky sights for February 15 23
Friday, February 15
By the time it becomes visible in Western Europe it will be a little fainter, and by its visibility in North America it will be down to 11th to 13th magnitude, receding into the distance near the Little Dipper. See our article Asteroid 2012 DA14 to Zip Past Earth, with detailed telescopic finding instructions and live video links.
Saturday, February 16
Sunday, February 17
Monday, February 18
Tuesday, February 19
Wednesday, February 20
When to look? Canopus is at its highest point when Beta Canis Majoris — Mirzim, the star three finger-widths to the right of Sirius — is at its highest point crossing the meridian. Look straight down from Mirzim then.
Thursday, February 21
Friday, February 22
Saturday, February 23
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).
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 (about magnitude –0.5) continues its excellent apparition in the evening twilight. Look for it low in the west-southwest as the sky darkens. No other point in the area is nearly so bright. See Mercury in February 2013.
Venus (magnitude –3.9) is lost in the glare of the Sun.
Mars (magnitude +1.2) is disappearing into the sunset, moving ever farther to Mercury's lower right.
Jupiter (bright at magnitude 2.4, in Taurus) dominates the high south at dusk and the southwest later. To its left is orange Aldebaran; to its right are the Pleiades. This whole group sets around 1 or 2 a.m. local time
In a telescope, Jupiter is shrinking as Earth pulls farther ahead of it in our faster orbit around the Sun. This week it shrinks from 41 to 40 arcseconds wide.
Saturn (magnitude +0.5, in Libra) rises in the east-southeast around 11 or midnight, well to the lower left of Spica. By the beginning of dawn Saturn is highest in the south — more or less between Spica, 18° to its right, and Antares farther to its lower left. Saturn is 4½° northwest of the wide double star Alpha Librae.
In a telescope Saturn's rings are tilted 19.3° from edge-on, their most open of the year (by just a trace).
Uranus (magnitude 5.9, in Pisces) is disappearing low in the west after dusk.
Neptune is in conjunction with the Sun.
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.
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