Sky at a Glance | March 9th, 2012

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.

    Comet Garradd, Feb. 25, 2012
    The gas and dust tails of Comet Garradd now point in almost opposite directions! Or so it appears. In fact, from Earth's perspective, the physically thin, flat dust tail appears nearly edge-on — as a broad fan spanning from left, through just below the comet's head as seen here, to the right nearly to the gas tail. We are looking almost straight down the tail. Paolo Candy in Italy took this image on February 25th. Stars are trails because Candy tracked multiple exposures on the comet's moving nucleus.
  • 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.

    The view in bright twilight
    Whether Jupiter and Venus will appear precisely level in the twilight this evening depends on your location. These sky scenes are always drawn for someone at latitude 40° north, longitude 90° west (the middle of North America).


    Look for the stars of Aries off to the planets' right. Mercury far below is greatly faded compared to last week.


    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).

    Sky Atlas 2000.0 (the color Deluxe Edition is shown here) plots 81,312 stars to magnitude 8.5. That includes most of the stars that you can see in a good finderscope, and typically one or two stars that will fall within a 50× telescope's field of view wherever you point. About 2,700 deep-sky objects to hunt are plotted among the stars.
    Alan MacRobert

    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

    Jupiter at 10:31 UT February 27, 2012
    The Great Red Spot was about to rotate off Jupiter's visible disk when Christopher Go in the Philippines took this image on February 27th local time. South is up.

    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 on March 5-6, 2012
    Syrtis Major is almost dead center in this Mars image taken by S&T's Sean Walker on the night of March 5–6. Mars was 13.9 arcseconds wide. He used a 12.5-inch reflector and stacked-video imaging. Don't expect views this good visually!


    South is up, and celestial east is to the right (the preceding side; Mars's morning side). Notice the bright cloud over Elysium at the 8 o'clock position here, and the edge of the North Polar Cloud Hood over Hellas at top. The North Polar Cap (NPC) has been shrinking in the Martian northern-hemisphere spring, exposing the dark collar around it. Just left of the cap, writes Walker, notice a yellowish apparent dust event.

    S&T: Sean Walker

    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.

    Saturn on Jan. 21, 2012
    Saturn's rings are tipped a good 15° from our line of sight. South is up. Note the very pale light band in the north temperate region, the remnant of the dramatic, billowing white outbreak that attracted so much attention last year. Christopher Go took this image on January 21, 2012.

    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.


    Like This Week's Sky at a Glance? Watch our new weekly SkyWeek TV short. It's also playing on PBS!


    To be sure to get the current Sky at a Glance, bookmark this URL:
    http://SkyandTelescope.com/observing/ataglance?1=1

    If pictures fail to load, refresh the page. If they still fail to load, change the 1 at the end of the URL to any other character and try again.

  • COMMENT