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This Week's Sky at a Glance

Some daily events in the changing sky for March 9 – 17

by Alan M. MacRobert

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Tony Flanders
Friday, March 9

  • Watch Venus and Jupiter, in the west at dusk, change orientation fast this week as they pass each other!

  • 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.

    Saturday, March 10

  • The waning gibbous Moon forms a nice triangle with Saturn and Spica, once they're well up by 10 or 11 p.m.

  • Tonight a 9.7-magnitude star in Orion will be occulted for up to 7 seconds by the fainter asteroid 57 Mnemosyne along a path crossing the U.S. from Delaware to southern California. The occultation happens within a few minutes of 4:19 Universal Time, depending on where you are. Charts and details.

  • Daylight-saving time begins (for most of North America) at 2 a.m. Sunday morning. Clocks "spring ahead" 1 hour.

    Sunday, March 11

  • With the Moon gone from the evening sky, start checking in once again on hardy Comet Garradd. Still about magnitude 6.5, it's not far off the bowl of the Little Dipper. That makes it well placed for viewing all night. See our article and chart in the March Sky & Telescope, page 60, or online.

    Monday, March 12

  • Venus and Jupiter are now almost at their closest together, appearing 3.1° apart this evening. Watch their orientation change drastically from day to day now that they're so close.

    Tuesday, March 13

  • Venus and Jupiter appear closest together tonight: 3.0°.

    Wednesday, March 14

  • Last-quarter Moon (exact at 9:25 p.m. EDT on this date). The Moon rises around the middle of the night. As dawn begins Thursday morning it's above the Teapot of Sagittarius.

    Thursday, March 15

  • This is the time of year when we in the mid-northern latitudes get our best evening look at the teeming Milky Way in the constellation Puppis, east and southeast of Canis Major. Explore some of the telescopic highlights here with Sue French's chart and article in the March Sky & Telescope, page 62.

    Friday, March 16

  • Jupiter and Venus have separated a bit to appear 4.0° apart now — still a head-turning spectacle during and after twilight!

  • Tonight Comet Garradd, 6th or 7th magnitude, passes about ¼° by the tail star of Draco: 4th-magnitude Lambda (λ) Draconis. See our article and chart in the March Sky & Telescope, page 60, or online.

    Saturday, March 17

  • As the stars come out, look south for brilliant Sirius. It's the bottom point of the Winter Triangle. The triangle's other corners are Procyon to Sirius's upper left, and Betelgeuse to Sirius's upper right (in the corner of Orion). Compared to the Summer Triangle, the winter one is brighter, more colorful, and equilateral!





    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 magazine of 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 effectively.

    You'll also want a good deep-sky guidebook, such as Sue French's new 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 classic if dated Burnham's Celestial Handbook.

    Can a computerized telescope replace charts? I don't think so — not for beginners, anyway, and especially not on mounts and tripods are less than top-quality mechanically (able to point with better than 0.3° repeatability). As Terence Dickinson and Alan Dyer say in their 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 still about the same height above the western twilight horizon as it was last week, far below or lower right of brilliant Venus and Jupiter. But it's fading: from a weak magnitude +0.5 on March 9th to an essentially invisible +2.4 on the 14th.

    Venus and Jupiter have their spectacular conjunction in the western evening sky this week! These are the two brightest celestial objects after the Sun and Moon, at magnitudes –4.3 and –2.1, respectively. They appear closest together, separated by 3°, on March 12, 13, and 14. After that, Jupiter moves away lower.

    In a telescope Venus is a brilliant white disk 20 arcseconds tall and slightly more than half lit (60% sunlit). Jupiter shows a much lower surface brightness, being farther from the Sun, but its apparent diameter is larger: 35 arcseconds.

    Mars (magnitude –1.1, in Leo) was at opposition on March 3rd and nearest Earth on March 5th. It shines bright fiery orange low in the east during twilight, and it dominates the eastern sky after dark. Regulus twinkles about 10° to its upper right. Mars shines highest in the south, in best telescopic view, by 11 or midnight.

    In a telescope Mars is still 13.8 or 13.9 arcseconds wide, the largest it will appear until 2014. See our Mars map and observing guide in the April Sky & Telescope, page 50.

    Saturn (magnitude +0.4, in Virgo) rises in the east around 9 or 10 p.m. and shines highest in the south around 3 a.m. Accompanying it 6° or 7° to the right or upper right is Spica, a little fainter at magnitude +1.0 (and bluer). In a telescope Saturn's rings are tilted 15° from our line of sight, their most open since 2007.

    Uranus and Neptune are 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. Eastern Daylight Time (EDT) is UT minus 4 hours.


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