Sky at a Glance | March 22nd, 2013

Comet PanSTARRS is fading as it crosses Andromeda near the Great Square of Pegasus. It's still in evening twilight for mid-northern latitudes, but the farther north you are, the darker a sky you can view it in now — or photograph it in! A map is on the March Sky & Telescope, pages 50 and 51. Bring binoculars or better, a wide-field telescope. See updates at SkyandTelescope.com/panstarrs.


Mid-evening view
As the Moon waxes toward full, it walks between Leo and mostly-dim Hydra.

Friday, March 22

  • Now that spring is here, Orion is in the southwest in the evening this week, leaning over to slide down to the western horizon. Orion's three-star belt is turning nearly horizontal. He is framed by the two brightest starlike points in the sky: Jupiter off to his right and Sirius to his left.

    Saturday, March 23

  • Left of the Moon this evening are Regulus and the Sickle of Leo, as shown here. Farther lower right of the Moon is Alphard, the heart of Hydra. To the right or upper right of the Moon, can you make out Hydra's dim head?

    Sunday, March 24

  • Look above the Moon this evening for Regulus. It's the bottom star of the Sickle of Leo.

    Monday, March 25

  • Look northwest right after dark for W-shaped Cassiopeia standing on end. The brightest part of the W is on the bottom.

    Tuesday, March 26

  • Full Moon tonight (exact at 5:27 a.m. Wednesday morning EDT). The Moon this evening is far below Leo and above Spica and Corvus.

    11 p.m. view
    With the Moon waning away from full, it rises ever later as it moves past Spica and Saturn.
    9 p.m. view
    Jupiter used to shine between Aldebaran and the Pleiades. But now it's moving eastward against the background stars and starting to leave them behind.

    Wednesday, March 27

  • With spring under way, Algol in Perseus is heading down in the northwest after dusk. Your last chance to catch Algol in one of its eclipses this season may be the one this evening or the one Saturday evening. Tonight Algol should be at minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:43 p.m. Pacific Daylight Time. Easterners will have a better shot on Saturday. Algol takes several additional hours to fade and to rebrighten.

    Thursday, March 28

  • Once the Moon rises this evening, look upper right of it for Spica and lower left of it for Saturn, as shown at right. You'll find more details here.

    Friday, March 29

  • The waning Moon rises in the east quite late this evening. Look above it for the planet Saturn.

  • This is the time of year when the dim Little Dipper juts to the right from Polaris (the Little Dipper's handle-end) during evening hours. The much brighter Big Dipper curls over high above it, "dumping water" into it.

    Saturday, March 30

  • Early Sunday morning, telescope users south of a line from central Florida through Oregon can watch the double star Beta Scorpii, magnitudes 2.6 and 4.8, emerge from behind the dark limb of the waning gibbous Moon. Map and timetables (for the bright component; the faint star emerges up to a minute or two earlier. Times are in Universal Time. Scroll down there to find the Reappearance timetable.)


    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 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

    a href="http://astro.christone.net/jupiter/" target="new_window">Christopher Go
    Jupiter on March 24, 2013
    In the 26 minutes between these images taken on March 24th, Jupiter's Great Red Spot rotated away around the preceding limb, and Io and its shadow moved far across the disk. South is up, and west (preceding) is to the left.
    a href="http://astro.christone.net/jupiter/" target="new_window">Christopher Go

    Mercury (brightening from magnitude +0.6 to +0.2 this week) is having a poor apparition very low in the dawn. Use binoculars to scan for it just above the east-southeast horizon about 30 minutes before sunrise.

    Venus and Mars are lost in the glare of the Sun.

    Jupiter (magnitude –2.1, in Taurus) comes into view high in the west after sunset, then descends as night grows late. Lower left of Jupiter is orange Aldebaran. Farther to Jupiter's lower right are the Pleiades. They all set in the west-northwest around the middle of the night.

    Jupiter is not as bright as it used to be, and in a telescope it has shrunk to 36 arcseconds wide – from 48″ around its opposition last December.

    Saturn (magnitude +0.3, in Libra) rises in the east-southeast only about an hour after the end of twilight now. Watch for it to make its appearance well to the lower left of Spica, and farther to the lower right of brighter Arcturus. Saturn shines highest in the south around 3 a.m. daylight saving time — more or less between Spica to its right, and Delta Scorpii and than Antares farther to its lower left. Saturn will come to opposition on the night of April 27th.

    Uranus and Neptune are out of sight in 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 Daylight Time (EDT) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.


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