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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 magazine of 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 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 classic if dated Burnham's Celestial Handbook.
Can a computerized telescope replace charts? I don't think so — not for beginners, anyway, and especially 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 0.0 and fading) is low in the west-northwest about 40 to 60 minutes after sundown. Well to its right are fainter Pollux and Castor.
Venus (magnitude –4.5) shines low in the east-northeast during dawn. Don't confuse it with Jupiter to its upper right. The two planets remain 5° or 6° apart this week, crossing the background of Aldebaran and the Hyades.
Mars (magnitude +0.8, in Virgo) shines orange in the southwest at dusk and lower in the west later. It's still about 25° from the Saturn-and-Spica pair to its left, but it's heading their way! Mars will shoot the gap between them in mid-August.
In a telescope Mars is gibbous and tiny (6.8 arcseconds wide), continuing to fade and shrink.
Jupiter (magnitude –2.0) shines low at dawn, to the upper right of Venus. See Venus above.
Saturn (magnitude +0.6, in Virgo) shines in the southwest as twilight fades. Below it by 5° is Spica. Later after dark they move lower to the west-southwest.
Uranus (magnitude 5.9, at the Pisces-Cetus border) is in the east-southeast before the first light of dawn.
Neptune (magnitude 7.9, in Aquarius) is in the south-southeast before 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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