This Week’s Sky at a Glance

Friday, May 25

  • Well to the right of the Moon this evening shine Pollux and Castor, the heads of the Gemini twins. They're lined up almost horizontally. Look well below the Moon for Procyon.

    This week, Scorpius is standing well up in the south-southeast by about 11 p.m. daylight saving time. The Sagittarius Teapot is just rising. How high they appear depends on your latitude. This shot was taken near 40° north.
    Jimmy Westlake

    Saturday, May 26

  • By late evening the summer constellation Scorpius is well up in the south-southeast, as shown at right. Look for its brightest star, fire-colored Antares, the Scorpion's heart. Antares' "outrigger" stars are just below it and to its upper right. Farther upper right is the diagonal three-star row of Scorpius's head, topped by Beta Scorpii.

    Sunday, May 27

  • Look above the Moon this evening for Regulus and, higher and fainter, Gamma Leonis. To the left of these three is Mars.

    Monday, May 28

  • Mars shines above the first-quarter Moon this evening.

    Tuesday, May 29

  • Bright Arcturus shines southeast of the zenith after dark. Vega, equally bright, shines less high in the east-northeast.

    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.

    The waxing gibbous Moon will line up under Spica and Saturn on Thursday the 31st. This view is drawn for a skywatcher near the middle of North America: at laititude 40° north, longitude 90° west. If you're elsewhere, the lineup may not be so straight. For clarity, the Moon is drawn three times its actual apparent size.

    Wednesday, May 30

  • Saturn and Spica are well to the left of the Moon this evening. Less far below the Moon, look for the four-star pattern of Corvus, the Crow, as shown here.

    Thursday, May 31

  • The gibbous Moon, Spica, and Saturn form an upward line this evening. How straight the line is will depend on when and where you're viewing from.

    Friday, June 1

  • By 10 or 11 p.m. (depending on your location) the Summer Triangle is up in the east. Its top corner is Vega: the brightest star in the eastern sky. Deneb is the brightest star to Vega's lower left. Look for Altair substantially farther to Venus's lower right.

    Saturday, June 2

  • The gibbous Moon shines in the south-southeast after dark. Look well to its lower left for orange Antares. Nearly halfway between the Moon and Antares is the row of three stars marking the head of Scorpius.


    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).

    The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but that's less than one star in an entire telescopic field of view, on average. By comparison, Sky Atlas 2000.0 plots 81,312 stars to magnitude 8.5, typically one or two stars per telescopic field. Both atlases include many hundreds of deep-sky targets — galaxies, star clusters, and nebulae — to hunt among the stars.
    Sky & Telescope

    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

    Venus is thinning every day. Dennis di Cicco captured this image in a bright blue sky a little before noon on May 27th, "while I was testing the setup I’ll be using to record the transit. It’s a video image made with a Tele Vue TV-85 telescope, 2.4X Barlow, and DMK video camera." Venus was 3.2% sunlit at the time.

    "I also captured a similar image the next morning, but the seeing wasn’t quite as good and Venus was an even more slender crescent. It’s interesting to see how quickly the crescent is changing as Venus draws closer to the Sun."

    S&T: Dennis di Cicco

    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.

    Although Mars was a mere 9.5 arcseconds wide on May 6th, Damian Peach recorded these extraordinarily fine images 29 minutes apart (the one on the right is the first). South is up. The North Polar Cap at bottom is matched by bright clouds covering the Hellas basin near top. The dark peninsula near the preceding limb (left here) is Syrtis Major.
    Damian Peach

    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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