This Week's Sky at a Glance
Some night sky sights for May 10 – 18
Chi Cygni bright. Chi (χ) Cygni, one of the brightest red long-period variable stars, is having an unusually bright maximum. For the last two weeks it's been about magnitude 3.8, 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 11 p.m., with the Northern Cross lying on its side. Comparison-star chart and two-year light curve up to the present courtesy AAVSO.
Note the time, then determine how long this is since new Moon occurred yesterday at 8:28 p.m. Eastern Daylight Time. The difference tells the Moon's current age. Does it break your personal record?
Saturday, May 11
Sunday, May 12
Monday, May 13
Tuesday, May 14
Wednesday, May 15
Friday, May 17
Scale model: If the Moon were a BB at reading distance 15 inches from your face, Regulus would be a house-size, blue-white-hot fireball at the Moon's actual distance.
Saturday, May 18
Find Antares about three fists at arm's length to the lower left of Saturn. Along the way you'll pass fainter Alpha Librae (not far from Saturn), and not-so-faint Delta Scorpii (relatively close to Antares).
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 glare of the Sun. But it's getting ready down there to come up for a very interesting evening-twilight apparition in the next few weeks.
Venus (magnitude –3.9) is beginning an evening apparition that will continue the rest of this year. Can you pick it up yet? Look about 20 minutes after sunset just above the west-northwest horizon (well to the lower right of Jupiter as seen from mid-northern latitudes).
And watch as Venus and Jupiter draw together this month, by 1° per day. They're 18° apart on May 10th and 11° on the 17th. Their conjunction comes on the 28th, when they'll be a close, 1° couple — with Mercury right alongside.
Mars remains hidden in the glare of the Sun.
Jupiter (magnitude 2.0, in Taurus) is the first "star" to come out in the west after sunset, a little lower every day. It sets around the end of twilight. Near it are the horn-tip stars of Taurus, Beta and Zeta Tauri. Much farther to Jupiter's upper right is bright Capella.
In a telescope, Jupiter is not only blurred by the poor low-altitude seeing but has shrunk to a disappointing 33 arcseconds wide, about as small as it ever gets.
Saturn (magnitude +0.2, in Libra) is two weeks past opposition and climbing higher in the evening sky. It glows low in the southeast after nightfall (lower left of Spica and farther lower right of Arcturus), and is highest in the south around midnight. Stay up late with your scope.
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 dawn.
Neptune (magnitude 7.9, in Aquarius) is low in the east-southeast just before dawn.
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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