Friday, May 25
Saturday, May 26
Sunday, May 27
Monday, May 28
Tuesday, May 29
A third of the way from Arcturus to Vega, look for dim Corona Borealis, the Northern Crown, with its one modestly bright star, Alphecca. Two thirds of the way from Arcturus to Vega is the dim Keystone of Hercules.
Wednesday, May 30
Thursday, May 31
Friday, June 1
Saturday, June 2
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 is buried deep in the glare of the Sun.
Venus (about magnitude –4.2 and fading) is now at the peak of its evening drama, dropping faster into the bright sunset every day. How many more days can you follow it with your naked eyes? With binoculars? Don't confuse it with Capella sparkling about 20° to its upper right. See our article, Venus Takes the Plunge.
In a telescope Venus is a dramatically thin crescent, just 4% sunlit on May 25th and 3% on the 30th, and about 55 arcseconds tall. You can see its crescent shape with firmly braced binoculars.
Venus is plunging toward inferior conjunction, when it will transit the face of the Sun on June 5–6 (on the afternoon of the 5th for North America). See our article Transit of Venus. Make your observing plans now! This will be the last Venus transit until 2117.
Mars (magnitude +0.3) shines orange in southern Leo, high in the south-southwest as twilight fades and lower in the southwest to west later in the evening. Spot Regulus 13° to 15° to Mars's lower right. They're moving farther apart daily. Fainter Gamma Leonis is 8° above Regulus; the three form a lengthening triangle.
In a telescope Mars is gibbous and tiny (8 arcseconds wide), continuing to fade and shrink as Earth leaves it behind in our faster orbit around the Sun.
Jupiter is buried deep in the sunrise.
Saturn (magnitude +0.5, in Virgo) shines high in the south at nightfall. Below it by nearly 5° is Spica, fainter and bluer. They set in the west before dawn.
Uranus (magnitude 5.9, at the Pisces-Cetus border) is very low in the east just before the first light of dawn.
Neptune (magnitude 7.9, in Aquarius) is in the southeast before dawn's first light.
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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