Sky at a Glance | March 11th, 2011

Friday, March 11

  • Look lower left of the Moon this evening for Aldebaran, an orange giant star 65 light-years away. About three times farther to the Moon's upper right shines brighter Capella, 42 light-years distant.

    Saturday, March 12

  • This evening until next Friday, Mercury is within 5° of brighter Jupiter very low in the western twilight — your easiest opportunity to spot Mercury all year. Mercury passes Jupiter on Tuesday, as shown below. Watch their changing configuration. Although they look close together, Jupiter is more than five times farther than Mercury; see article.

  • First-quarter Moon (exact at 6:45 p.m. Eastern Standard Time). The Moon is between the horn stars of Taurus: Beta (β) and Zeta (ζ) Tauri.

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

    Twilight view, looking low
    Find a spot with a clear, open view low to the west, and you can watch Mercury passing Jupiter in twilight from March 13 to 16. Click on image for an animation!


    Feel free to use these illustrations anywhere — just credit Sky & Telescope magazine and include a link to SkyandTelescope.com.

    Credit: Sky & Telescope magazine

    Sunday, March 13

  • The third-brightest star that the Moon occults (covers) this year for North America slides behind the Moon's dark edge after sunset, for observers in the Northeast and along the Eastern Seaboard. The star is Mu Geminorum, magnitude 3.2 and orange-red. The Moon will be in fine view very high in the south; see article.

  • Binoculars or a telescope show the 6th-magnitude star 46 Virginis only 9 arcminutes from Saturn tonight — looking like a big, wayward Saturnian moon.

    Monday, March 14

  • 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 probably 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 leap to 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.

    Tuesday, March 15

  • Mercury and Jupiter appear closest together after sunset, 2° apart.

    Wednesday, March 16

  • The Moon this evening lies on a huge line from Regulus (to its left or lower left) through Procyon to Orion.

    Thursday, March 17

  • For the next two weeks Mercury continues its best evening apparition of 2011 (for skywatchers at mid-northern latitudes) — even as Jupiter slides lower and lower down below it.

  • The brightest star nearly a fist-width above the Moon this evening is Regulus.

    Friday, March 18

  • By mid-evening, look far to the lower left of the Moon for Saturn and, below Saturn, twinkly Spica on the rise. Far to their left sparkles brighter Arcturus, the "Spring Star."

    Late-evening view
    The big bright Moon guides the way to Saturn and its springtime surroundings.
    Alan MacRobert

    Saturday, March 19

  • Full Moon (exact at 2:10 p.m. Eastern Daylight Time). The Moon is in Virgo, along with Saturn and Spica as shown here.



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    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).

    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
    must have a detailed, large-scale sky atlas (set of charts). The standards are the Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger and deeper 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 Sky Atlas 2000.0 Companion by Strong and Sinnott, or the more detailed and descriptive Night Sky Observer's Guide by Kepple and Sanner, or the classic if dated Burnham's Celestial Handbook.

    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

    Saturn on Feb. 6, 2011
    Saturn's dispersing white spot "looks like a comet," wrote Christopher Go. As of March 2nd its head had moved far around the planet to about System III longitude 120°. This image (taken February 6th) exaggerates its contrast. South is up. Click for animation of several images spanning 33 minutes of Saturn's rotation. And see an even more awesome Cassini image.

    Mercury and Jupiter (magnitudes –1 and –2.1, respectively) pass each other low in the western twilight this week, as shown at the top of this page. You'll need a good open view low toward the western horizon. As twilight fades, you'll probably pick up brighter Jupiter first. Use it to locate Mercury. They appear closest together on Monday and Tuesday, March 14th and 15th, 2° apart. That's about the width of your thumb at arm's length.

    By a remarkable coincidence, both planets pass through perihelion this week (closest to the Sun in their orbits). Mercury has a perihelion every 88 days, but Jupiter has one only every 12 years.

    Venus (magnitude –4.0, in Capricornus) shines low in the southeast during dawn.

    Mars is out of sight behind the glare of the Sun.

    Saturn on Feb. 11, 2011
    The other side of Saturn, imaged by Go on February 11th. The dark, reddish South Equatorial Belt can be seen just south of the ring. South is up.

    Saturn (magnitude +0.4, in Virgo) rises around 8 or 9 p.m., but it's best seen in a telescope much later in the night when it gains high altitude. It's highest in the south around 2 or 3 a.m. daylight saving time. Spica, slightly fainter, shines about 10° below Saturn all evening and past midnight. About half as far above or upper right of Saturn is dimmer Gamma Virginis (Porrima).

    In a telescope, Saturn's months-old white spot has spread into a streak far around the planet, as seen here. Saturn's rings are 9° from edge on. See how many of Saturn's satellites you can identify in your scope using our Saturn's Moons tracker.

    Uranus and Neptune are hidden 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 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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