This Week’s Sky at a Glance

Friday, January 25

  • The Moon this evening shines not quite midway between Procyon, to its lower right, and Pollux, to the Moon's upper left.

    Saturday, January 26

  • Full Moon (exact at 11:38 p.m. EST). The Moon is in dim Cancer, with Procyon shining off to its right or upper right during evening, and Pollux and Castor above it.

  • Algol in Perseus is at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 6:26 p.m. EST. Watch it gradually rebrighten though the evening.

    As it passes full and starts to wane, the Moon moves down through the lair of the Lion.

    Sunday, January 27

  • The Moon shines high in the east by 9 p.m. Lower left of it, by roughly a fist-width at arm's length, sparkles Regulus in Leo, as shown here. The Sickle of Leo extends upper left from Regulus. The emergence of Leo in the evening sky is always an early sign that spring is eventually coming.

    Monday, January 28

  • Once the waning gibbous Moon is well up in the east in mid- to late evening, look upper left of it for Regulus with the Sickle of Leo extending beyond, as shown here. Look about twice as far to the Moon's right for Alphard, the fire-colored heart of Hydra.

    Tuesday, January 29

  • Around 9 or 10 p.m. this week (depending on how far east or west you live in your time zone), brilliant Sirius is at its highest due south.

  • Sirius is the brightest star in the night sky — and are you far enough south to see the second brightest, Canopus? In one of the many interesting coincidences that devoted skywatchers know about, Canopus lies almost due south of Sirius: by 36°. That's far enough south that it never appears above your horizon unless you're below latitude 37° N (southern Virginia, southern Missouri, central California). And there, you'll need a flat south horizon. Canopus transits the sky's north-south meridian just 21 minutes before Sirius does.

    When to look? Canopus is there at its highest point when Beta Canis Majoris — Mirzim, the star about three finger-widths to the right of Sirius — is at its highest point crossing the meridian. Look straight down from Mirzim then.

    Wednesday, January 30

  • Saturn is at western quadrature: 90° west of the Sun in the morning sky.

  • You may know about the "odd couple" open star clusters M46 and M47 in Puppis, in the cold depths east of Sirius. But what about the lesser-known telescopic clusters, and two planetary nebulae, within just a few degrees of them? Explore their rich area with Sue French's Deep-Sky Wonders column and charts in the February Sky & Telescope, page 56.

    Saturn rises in the middle of the night this week and shines high during dawn. The Moon is positioned here for the middle of North America. The blue 10° scale is about the width of your fist at arm's length.

    Thursday, January 31

  • Jupiter's moon Io crosses Jupiter's face from 7:59 to 11:09 p.m. EST. Io's tiny black shadow follows behind across Jupiter from 10:10 p.m. to 12:21 a.m. EST. Meanwhile, Jupiter's Great Red Spot (actually pale orange-tan) crosses the planet's central meridian around 8:07 p.m. EST.

    For all of Jupiter's satellite events and Great Red Spot transit times, good worldwide, get our new JupiterMoons app.

    Friday, February 1

  • The sky's biggest well-known asterism (informal star pattern) is the Winter Hexagon or Winter Circle. It fills the sky toward the east and south these evenings. Start with brilliant Sirius at its bottom. Going clockwise from there, march through Procyon, then Pollux and Castor, then Menkalinen and Capella overhead, down to Aldebaran (overshone by Jupiter this season!), down to Rigel, and back to Sirius.

    Saturday, February 2

  • Your latitude makes a big difference in how the constellations appear. (Your longitude does not.) For instance, if you're as far north as 46° — roughly Portland, Minneapolis, Montreal, central France ° bright Capella passes straight through your zenith sometime around 8 or 9 p.m. If you're as far south as 21° N — roughly Guadalajara, Cuba, the mid-Sahara, Kolkata — Jupiter currently crosses straight overhead in the evening. Wherever you are, they now pass closest to your zenith exactly one hour apart, with Jupiter going first.

  • Not-the-Superbowl Star Party. Donald Lubowich, coordinator of astronomy outreach at Hofstra University, writes: "For the past six years I have run a Super Bowl Star Party targeting women, girls, and the 65% of the U.S. that does not watch the Super Bowl. I encourage astronomers, astronomy clubs, and astronomy educators to create a similar program, or to bring a portable scope to their own Super Bowl parties." It's tomorrow. Jupiter, the Orion Nebula, the Perseus Double Cluster and more will be nice and high.


    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 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 beloved if dated Burnham's Celestial Handbook.

    Can a computerized telescope replace charts? Not for beginners, I don't think, and certainly 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 deep in the sunset.

    Venus (magnitude –3.9) is just above the southeast horizon 20 minutes before your local sunrise. It's getting lower each morning. Bring binoculars.

    Mars (magnitude +1.2) still glimmers very low in the west-southwest in the fading glow of sunset. Don't confuse it with Fomalhaut well to its left.

    Jupiter on January 27th. South is up. The orange Oval BA, on the central meridian near top, has now moved far ahead of the Great Red Spot (near the right limb) after passing it in mid-September. Complex bluish festoons jut equatorward from the south edge of the North Equatorial Belt.

    Jupiter (magnitude –2.5, in Taurus) is the first "star" to come out high in the southeast after sundown. It dominates the high south after dinnertime, with orange Aldebaran lower left or left of it, and the Pleiades to its upper right or right.

    For many weeks, Jupiter has been drawing closer to forming a straight line with Aldebaran and Pleiades. It'll never get there. Jupiter reaches its stationary point on January 30th, when it ceases its retrograde (westward) motion against the stars and starts moving back eastward.

    In a telescope, Jupiter has been slowly shrinking as Earth pulls ahead of it in our faster orbit around the Sun. It appears about 44 arcseconds wide. The 5th-magnitude star 0.1° south of it this week is Omega-2 Tauri.

    Saturn (magnitude +0.6, in Libra) rises in the east-southeast around 1 a.m. local time. By the beginning of dawn it's fairly high in the south — more or less between Spica, far to its right, and Antares farther to its lower left.

    Uranus (magnitude 5.9, in Pisces) is still in view in the southwest right after dark. Finder chart.

    Neptune (magnitude 8.0) is lost in the sunset glow in the background of Mars.


    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 Standard Time (EST) equals Universal Time (also known as UT, UTC, or GMT) minus 5 hours.


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