This Week’s Sky at a Glance


Chi Cygni still bright. Chi (χ) Cygni, one of the brightest red long-period variable stars, is having an unusually bright maximum. It reached magnitude 3.8 earlier in May and is just beginning to fade, still very plain to the naked eye. Look for it adding to the bottom part of the shaft of the Northern Cross, between Eta (η) and Beta (β) Cygni. Cygnus is reasonably well up in the east by about 10 p.m., with the Northern Cross lying on its side. Comparison-star chart, and two-year light curve up to the present courtesy AAVSO.


Closer and closer....
The bright planets in these scenes are plain to the naked eye, but the fainter stars may be hard or impossible to see in bright twilight. The scenes are about three fist-widths at arm's length wide. They're drawn for the middle of North America but will be good enough throughout the world's mid-northern latitudes. For the scene every day, plus high-res versions for print use, see our press release. Pass them on!

Friday, May 24

  • Jupiter, Venus, and Mercury, low in the afterglow of sunset, are now officially a "trio": they fit within a 5° circle. This means you could just about cover them with a golf ball at arm's length. And they'll fit in the view of most binoculars. They'll stay at least this close through next Wednesday the 29th. This evening, Venus and Mercury appear their closest together.

    For sky scenes showing the group's progress every day through May 31st — which you are welcome to republish elsewhere with credit (the video too!) — see our press release. It also has hi-res versions of the scenes.

  • Full Moon (exact at 12:25 a.m. EDT tonight). The Moon is nearly at perigee, so it appears a tiny trace bigger than average.

  • The dazzling Moon occults (covers) the 2nd-magnitude star Beta Scorpii this evening for much of the eastern U.S. except the Northeast. See the May Sky & Telescope, page 52, for more info and a map.

    Saturday, May 25

  • The Jupiter-Venus-Mercury trio continues shrinking. Above it, by contrast, the enormous Arch of Spring spans much of the western sky as twilight dims. Its highest part is the Pollux-and-Castor pair, roughly horizontal and about three finger-widths apart. Look far to the lower left of Pollux and Castor for Procyon, and farther to their lower right for Menkalinen and then bright Capella.

    Sunday, May 26

  • Mercury, Venus, and Jupiter are bunched their tightest this evening, forming a little triangle just 2° on a side. Look in the northwest 30 or 40 minutes after sunset. Think photo opportunity.

  • The best time to view Venus at high power in a telescope is in late afternoon well before sunset, when it's still at a high altitude in relatively steady air. All week Mercury and Jupiter are in the same vicinity, but they're tougher catches in broad daylight. Pick them up them using the day-by-day finder chart for all three above the afternoon Sun in the June Sky & Telescope, page 51.

    Monday, May 27

  • This is the time of year when Spica, the brightest star of Virgo, shines due south just after dark. It's far to the lower right of high, bright Arcturus. Its name means "ear of wheat," and the Virgo stick figure is holding it in her hand without paying much attention. To Spica's lower right (by about a fist and a half at arm's length) is the four-star pattern of Corvus the Crow, eyeing it greedily. This year Corvus has Saturn to try to steal too. Saturn is glowing to Spica's left, noticeably brighter.

    Tuesday, May 28

  • Jupiter and Venus are now at their closest together, 1° apart low in the west-northwest after sunset. Mercury is above them.

    Wednesday, May 29

  • Here it is not even June yet, and the Big Dipper after dusk is already turning around to hang down by its handle. Look for it high in the northwest.

    Thursday, May 30

  • Vega is the brightest star in the east-northeast these evenings. The main part of its little constellation, Lyra, hangs from it to its lower right.

    Friday, May 31

  • Mercury, Venus, and Jupiter have stretched out into a nice straight line 7° long. Look low in the northwest after sunset. The line will continue to lengthen day by day, as Jupiter descends to the horizon and Mercury pulls a bit higher above Venus.

  • Last-quarter Moon (exact at 2:58 p.m. EDT).

    Saturday, June 1

  • Vega, shining brightly in the east-northeast, it currently the top star of the huge Summer Triangle. Look to Vega's lower left, by two or three fists at arm's length, for Deneb. The third star of the Summer Triangle is Altair, considerably farther to Vega's lower right. Altair is barely rising in the east as dusk fades away this week. How early in the evening can you spot it?


    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).

    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 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, Venus, and Jupiter are bunched together low in the afterglow of sunset, forming a new configuration each evening. They're magnitudes –1, –4, and –2, respectively. From the 24th through 29th the three form a "trio," fitting in a circle 5° in diameter. They're bunched most tightly, fitting in a 2½° circle, on the evening of the 26th.

    Mercury and Venus appear closest together, just under 1½° apart, on the 23rd and 24th. Venus and Jupiter are closest, 1° apart, on the 28th.

    See our article The May-June Planet Dance. For day-by-day sky scenes through the 31st, which you are welcome to republish elsewhere with credit (the video too!), see our press release.

    Mars is hidden behind the glare of the Sun.

    "Here is an image of Saturn taken on April 20th from Mt. Olympus, Cyprus (1950m altitude) under excellent observing conditions," writes Damian Peach. "Probably the best view I've had of the planet in the last few years. Periods of extremely steady seeing prevailed and allowed a very clear view of the planet and rings. A really memorable and enjoyable night on Cyprus's highest peak."

    North is up. Note the north polar hexagon. The thin whitish zone at mid-northern latitudes is the remains of the great storm of 2010–11. Several brightness minima can be seen across the ring system. Peach used a 14-inch Celestron Schmidt-Cassegrain telescope.


    Saturn (magnitude +0.2, in Libra) glows in the southeast during twilight, with Spica to its upper right and Arcturus twice as far to its upper left. It's highest in the south not long after dark.

    In a telescope, Saturn's rings are nicely tilted 18° from our line of sight. See our guide "Scrutinizing Saturn" in the May Sky & Telescope, page 50, or the shorter version online. And identify Saturn's many moons at any time and date with our SaturnMoons utility or handier app.

    Uranus (magnitude 5.9, in Pisces) is low in the east at the beginning of dawn.

    Neptune (magnitude 7.9, in Aquarius) is in the southeast just before dawn begins.


    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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