Watch the Moon pass Jupiter and company this week. (These scenes are drawn for the middle of North America. European skywatchers: move each Moon symbol a quarter of the way toward the one for the previous date. In the Far East, move it halfway. For clarity, the Moon is shown three times actual size.)

Sky & Telescope diagram


Friday, February 15

  • After dark, look to the right of the crescent Moon by roughly a fist-width at arm's length for the two or three leading stars of Aries (outside the frame above). They're lined up almost vertically.
  • Close flyby of asteroid 2012 DA14. This roughly 50-meter asteroid missed Earth today by only 18,000 miles (28,500 km) around 19:25 Universal Time (2:25 p.m. Eastern Standard Time). It was then as bright as 8th magnitude, moving across the stars by 0.8° per minute — and in nighttime view from easternmost Europe, Asia, and much of Australia.

    By the time it becomes visible in Western Europe it will be a little fainter, and by its visibility in North America it will be down to 11th to 13th magnitude, receding into the distance near the Little Dipper. See our article Asteroid 2012 DA14 to Zip Past Earth, with detailed telescopic finding instructions and live video links.

  • Algol should be at minimum light for a couple hours centered on 8:12 p.m. EST.

    Saturday, February 16

  • Bright Jupiter shines upper left of the Moon. Aldebaran is to Jupiter's left, and the Pleiades are a little farther to Jupiter's right.
  • Mercury is at greatest elongation, 18° east of the Sun in evening twilight. A telescope shows (in reasonably good seeing) that this tiny little sphere, just 7 arcseconds wide, is now half-lit.

    Sunday, February 17

  • The first-quarter Moon shines to the right of Jupiter just after dark, as shown above. Watch it move closer to Jupiter through the evening, by about one Moon-diameter per hour, as they tilt down toward the west. They set around 1 or 2 a.m.

    Monday, February 18

  • The Moon now shines to the left or upper left of Jupiter and Aldebaran, drawing farther away from them through the evening.

    Tuesday, February 19

  • The Moon after dark stands straight over Orion, who's standing straight upright in the south.

    Wednesday, February 20

  • Have you ever seen Canopus, the second-brightest star after Sirius? 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 at its highest point when Beta Canis Majoris — Mirzim, the star three finger-widths to the right of Sirius — is at its highest point crossing the meridian. Look straight down from Mirzim then.

    Thursday, February 21

  • Early this evening, look lower right of the Moon for Procyon and upper left of the Moon for Castor and Pollux. Much farther to the lower right of Procyon shines bright Sirius.

    Friday, February 22

  • This evening the Moon is left of Procyon and below Castor and Pollux.

    Saturday, February 23

  • At this time of year, the Big Dipper stands on its handle in the northeast during evening. The top of the Dipper — the two Pointer stars pointing left to Polaris — are now at exactly Polaris's height around 8 p.m. (depending on where you live in your time zone).

    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).

    Pocket Sky Atlas

    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

    Jupiter on Feb. 6, 2013

    The shadow of Ganymede was passing the Great Red Spot when Christopher Go took this image of Jupiter at 10:59 UT February 6th. South is up. Note the white outbreaks in the South Equatorial Belt downstream from the Great Red Spot. Another is below them in the North Equatorial Belt.

    Christopher Go

    Mercury (about magnitude –0.5) continues its excellent apparition in the evening twilight. Look for it low in the west-southwest as the sky darkens. No other point in the area is nearly so bright. See Mercury in February 2013.

    Venus (magnitude –3.9) is lost in the glare of the Sun.

    Mars (magnitude +1.2) is disappearing into the sunset, moving ever farther to Mercury's lower right.

    Jupiter (bright at magnitude –2.4, in Taurus) dominates the high south at dusk and the southwest later. To its left is orange Aldebaran; to its right are the Pleiades. This whole group sets around 1 or 2 a.m. local time

    In a telescope, Jupiter is shrinking as Earth pulls farther ahead of it in our faster orbit around the Sun. This week it shrinks from 41 to 40 arcseconds wide.

    Saturn and moons on Jan. 26, 2013

    This extraordinary amateur image of Saturn was captured by Darryl Pfitzner Milika in Australia on January 26th. He used a 14-inch Celestron Schmidt-Cassegrain scope and an ASI120MM planetary video camera for frame-stacking. Just visible is the hexagonal shape of the storm that surrounds Saturn's north pole. The hexagon shape was first discovered by the Cassini spacecraft in 2007. South is up.

    Also visible in his image are four of Saturn's moons. From left: Dione, Enceladus, Mimas (!), and Tethys. Click for larger view.

    Darryl Pfitzner Milika


    Saturn (magnitude +0.5, in Libra) rises in the east-southeast around 11 or midnight, well to the lower left of Spica. By the beginning of dawn Saturn is highest in the south — more or less between Spica, 18° to its right, and Antares farther to its lower left. Saturn is 4½° northwest of the wide double star Alpha Librae.

    In a telescope Saturn's rings are tilted 19.3° from edge-on, their most open of the year (by just a trace).

    Uranus (magnitude 5.9, in Pisces) is disappearing low in the west after dusk.

    Neptune is in conjunction with the Sun.

    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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