This Week's Sky at a Glance
Some night sky sights for July 12 20
Friday, July 12
Saturday, July 13
Sunday, July 14
Monday, July 15
The Moon occults (hides) Spica for skywatchers in Hawaii and parts of Central and South America; see map and timetables.
Tuesday, July 16
Wednesday, July 17
Thursday, July 18
Friday, July 19
Some times of the star's disappearance: in western Massachusetts, 12:38 a.m. EDT; Atlanta, 12:32 a.m. EDT; Chicago, 11:10 p.m. CDT; Winnipeg, 10:50 p.m. CDT; Kansas City, 11:00 p.m. CDT; Austin, 11:07 p.m. CDT; Denver, 9:39 p.m. MDT. Start watching early.
Saturday, July 20
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.
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). 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 is hidden in the glow of sunrise.
Venus (magnitude –3.9) shines brightly low in the west-northwest in evening twilight. In a telescope it's still small (12 arcseconds) and gibbous (87% sunlit). But for the rest of the year, watch it grow in size and wane in phase until becoming a long, ultra-thin crescent.
Mars and Jupiter are low in the east-northeast during early dawn. Jupiter is far and away the brightest at magnitude –1.9. Look just upper right of it for Mars, magnitude +1.6. Binoculars help. Jupiter is drawing closer to Mars daily. They'll pass just 3/4° apart on the morning of July 22nd.
Saturn (magnitude +0.6, in Virgo) glows in the southwest after dusk, with Spica 12° to its lower right. Look about as far to Saturn's left for fainter Alpha Librae. Just ½° above Saturn this week is dim Kappa Virginis, magnitude 4.3.
Uranus (magnitude 5.8 in Pisces) and Neptune (magnitude 7.9 in Aquarius) are high in the southeast and south, respectively, before the beginning of dawn. 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 Daylight Time (EDT) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.
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