Sky at a Glance | March 1st, 2013


Where to Find Comet PanSTARRS

Looking west in bright twilight
Look west after sunset near the horizon. Binoculars may be needed to pick Comet PanSTARRS out of the bright sky. Look too early and the sky will be too bright; too late and the comet will be too low. On the altitude scale at left, 10° is about the width of your fist held at arm's length.


This diagram is drawn for a viewer near 40° north latitude (Denver, New York, Madrid) 30 minutes after sunset. If you're south of there, the comet will be a little higher above your horizon early in the month than shown here. North of 40°, it will be a little lower early in March than shown here.


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Swinging toward its March 10th closest approach to Sun, Comet PanSTARRS emerges above the western sunset horizon this week for observers at mid-northern latitudes. Bring binoculars or a wide-field telescope; it's unlikely to be brighter than about 2nd magnitude, not necessarily easy to spot low in twilight through thick air.

The farther south you are, the earlier the date when you may first pick it up. As of February 28th it was already being seen naked eye (faintly) from the Southern Hemisphere. Next week the comet should come into its best visibility for mid-northern latitudes.

See our updates at SkyandTelescope.com/panstarrs. Get out and look!


Around 11 p.m.
Saturn rises with the Moon late tonight....
Dawn view
...and they shine high by dawn.

Friday, March 1

  • Around 11 p.m. this evening (depending on where you live), the waning gibbous Moon rises with Saturn glowing a few degrees to its left, as shown here. The pair remain close for the rest of the night and are high in the south-southwest by dawn Saturday morning, as shown below.

    Saturday, March 2

  • Now that March has begun, Sirius takes over from Orion to stand at its highest in the south soon after dark.

    Sunday, March 3

  • Jupiter's moon Europa disappears into eclipse by Jupiter's shadow around 7:10 p.m. EST, after reappearing from behind Jupiter's eastern limb just 14 minutes earlier. Io disappears behind Jupiter's other side 10 minutes later. Europa then reappears out of eclipse at 9:38 p.m. EST, followed by Io at 10:50 p.m. EST.

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

    Monday, March 4

  • With Sirius on the meridian after dinnertime, so is the Winter Triangle — since Sirius is its bottom corner. The other two are Procyon to its upper left and Betelgeuse to its upper right. The Winter Triangle is almost perfectly equilateral: all three stars are 26° from each other within about 1° accuracy.

  • Last-quarter Moon (exact at 4:53 p.m. EST).

    Tuesday, March 5

  • On the traditional divide between the winter and spring sky is the dim constellation Cancer. It's between Gemini to its west and Leo to its east. Cancer has a unique feature: the Beehive Star Cluster, M44, in its middle. The Beehive shows to the naked eye only if your light pollution is slight. Look for it a little less than halfway from Pollux to Regulus. With binoculars it's a snap.

    Wednesday, March 6

  • Following behind Sirius and Canis Major across the sky is Milky-Way-rich Puppis. Hunt out its many telescopic open clusters with Sue French's Deep-Sky Wonders chart and article in the March Sky & Telescope, page 56.

    Thursday, March 7

  • Algol in Perseus should be at minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:58 p.m. Eastern Standard Time. Algol takes several additional hours to fade and to rebrighten.

    Friday, March 8

  • Jupiter is 5° from Aldebaran high in the west after dark. But it's now passing only 2° from fainter (3.5-magnitude) Epsilon Tauri, the other tip of the Hyades V pattern, located almost between them.

    Saturday, March 9

  • The Big Dipper glitters high in the northeast these evenings, standing on its handle. You probably know that the two stars forming the front of the Dipper's bowl (currently on top) are the Pointers; they point to Polaris, currently to their left.

    And, you may know that if you follow the curve of the Dipper's handle out and around by a little more than a Dipper length, you'll arc to Arcturus, now rising in the east.

    But did you know that if you follow the Pointers backward the opposite way, you'll land in Leo?

    Draw a line diagonally across the Dipper's bowl from where the handle is attached, continue far on, and you'll go to Gemini.

    And look at the two stars forming the open top of the Dipper's bowl. Follow this line past the bowl's lip far across the sky, and you crash into Capella.

  • Daylight-saving time begins at 2 a.m. Sunday morning in most of North America. Clocks spring ahead an hour.


    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 March 4, 2013
    As Jupiter shrinks into the distance, its most striking characteristic in amateur telescopes is the single, broad South Equatorial Belt (above center) contrasting with the paired North Equatorial and North Temperate Belts. South here is up. Note the Great Red Spot at right, in a well-defined white Red Spot Hollow. Compare it to the slightly smaller and paler orange Oval BA left of the central meridian. Blue festoons mark the north edge of the bright Equatorial Zone but not its south edge.
    Saturn on March 2, 2013
    Saturn on March 2, 2013, imaged by Christopher Go. South is up. Note the bright Equatorial Zone and, tougher to see, the thin whitish band at mid-northern latitudes: the last remnant of the great white storm that broke out at this latitude in December 2010.

    Mercury, Venus, and Mars are hidden in the glare of the Sun.

    Jupiter (bright at magnitude –2.3, in Taurus) comes into view high in the south-southwest after sunset and dominates the southwest to west later in the evening. Left of Jupiter is orange Aldebaran; farther to its lower right are the Pleiades. They all set in the west-northwest around midnight or 1 a.m.

    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 39 to 38 arcseconds wide.

    Saturn (magnitude +0.4, in Libra) rises in the east-southeast around 10 or 11 p.m. Watch for it to come up well to the lower left of Spica and farther to the lower right of brighter Arcturus. Saturn shines highest in the south before the first light of dawn — more or less between Spica to its right and Antares farther to its lower left.

    Uranus is sinking away in the west after sunset.

    Neptune is behind the glare of 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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