Sky at a Glance | March 5th, 2010

Some daily events in the changing sky for March 5 – 13.

Friday, March 5

  • Before dawn Saturday morning, look south for the Moon — with Antares to its left and the stars of Scorpius's head around it, as shown below.

    Dawn view
    Get up very early in March and you can catch a preview of the summer constellations Scorpius and Sagittarius — if you look before the sky grows too bright!

    Saturday, March 6

  • Before dawn Sunday morning, look south for the last-quarter Moon — with Antares and the head of Scorpius now to its right, as shown above.

    Winter Triangle
    The Winter Triangle spans an area of the Milky Way rich in telescopic deep-sky objects. Click image for larger view.

    Sunday, March 7

  • This is the time of year when bright Sirius stands at its highest due south right after dark. It forms the big, equilateral Winter Triangle with Betelgeuse to its upper right and Procyon to its upper left. Run the line from Sirius through Procyon farther onward, and you'll hit Mars.

    Monday, March 8

  • If you've got an 8-inch or larger scope, have you ever tried for the faint companion of Sirius? It's a tricky challenge and requires a night of excellent, steady seeing (being 10,000 times fainter than Sirius A). But it's now 9.1 arcseconds due east of the bright primary, wider than it's been for nearly three decades. For more information see the March Sky & Telescope, page 47, and especially the February 2008 issue, page 33.

    Tuesday, March 9

  • Have you ever seen Canopus, the second-brightest star after Sirius? In one of the many interesting coincidences that devoted skywatchers know about, 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.

    When to look? Canopus is always at its highest point when Beta Canis Majoris (Mirzim, the bright star to the right of Sirius) is at its highest point crossing the meridian due south. Look straight down from it.

    Wednesday, March 10

  • Leo is a land of double stars. Tour them using Richard Jaworski's "Seeing Double" article and chart in the March Sky & Telescope, page 73.

    Thursday, March 11

  • Mars halts its retrograde (westward) motion against the stars of Cancer today and begins moving east again.

    Friday, March 12

  • 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 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 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 13

  • Daylight saving time begins at 2 a.m. Sunday morning for most of the U.S. and Canada. Clocks spring ahead.


    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.

    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

    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 Sky Atlas 2000.0 or the smaller Pocket Sky Atlas) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic Burnham's Celestial Handbook). Read how to use them effectively.

    Can a computerized telescope take their place? I don't think so — not for beginners, anyway (and especially not on mounts that are less than top-quality mechanically). 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

    Mars on March 3, 2010
    Mars is gibbous now; it's more than a month past opposition. The north polar cap (bottom) remains big and bright despite the advance of spring in the Martian northern hemisphere. At center-left is dark Syrtis Major; at upper right are dark Sinus Sabaeus and Sinus Meridiani. At top, the Hellas region is slightly bright.


    Christopher Go in the Philippines took this image at 14:00 UT March 3rd, when the central meridian longitude was 321°. Stacked-video imagery like this can show detail on a planet much more clearly than the eye can see through the same telescope.

    Christopher Go

    Mercury is hidden behind the glare of the Sun.

    Venus (magnitude –3.9) is slowly emerging from the sunset. Look for it due west just above the horizon about 30 minutes after sundown. Binoculars may help. Venus will gradually creep up into better twilight visibility for the next three months.

    Mars, now faded to magnitude –0.4, shines very high in the east at dusk and toward south by around 9 p.m. It's in Cancer, below Pollux and Castor after dusk and left of them later in the evening.

    In a telescope Mars is gibbous and shrinking: from 11.6 to 10.8 arcseconds in diameter this week. Its bright north polar cap remains the most visible marking. Identify other surface features using the Mars map and observing guide in the December Sky & Telescope, page 57.

    Jupiter is hidden behind the glare of the Sun.

    Saturn with Rhea and its shadow in transit, March 9, 2010
    is very red, while the North Polar Region is dark."

    The small white spot associated with Saturn Electrostatic Discharges (SEDs) is barely visible just south (upper left) of Rhea's shadow. "The SED [spot] seems to be prominent again, and the radio anomaly has been detected by the Cassini spacecraft as reported by Georg Fischer." writes Go. "The SED's location is around System III longitude 0°."

    Go images the planets with a Celestron 11 scope on an AP900GTO mount using a DMK 21F04 camera. Stacked-video images like this usually show more detail than the eye can see through the same telescope. South is up. Click image for a sequence of views (with north up)." credits="Christopher Go" width="" height="" align="right"]
    Saturn (magnitude +0.6, in western Virgo) rises in the east in twilight, shines higher in the southeast later in the evening, and stands highest in the south around 1 a.m. In a telescope, Saturn's rings are tilted only 3.6° from edge-on to us. They'll narrow further to 1.7° in May.

    Uranus and Neptune are behind the glare of the Sun.

    Pluto (magnitude 14) is up in the southeast before dawn.

    All descriptions that relate to your horizon or zenith — 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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