Sky at a Glance | December 30th, 2011

What to See with Your New Telescope. As the gift-giving season comes to an end, maybe you've got a shiny new telescope to call your own. Read our article on how to get started using it! What to See with Your New Telescope.


Friday, Dec. 30

  • Look upper right of the Moon after dinnertime for the Great Square of Pegasus balancing on one corner. It's a little larger than your fist held at arm's length.

  • Jupiter's Great Red Spot crosses Jupiter's central meridian around 7:59 p.m. EST.

  • The eclipsing variable star Algol is at minimum brightness, magnitude 3.4 instead of its usual 2.1, for about two hours centered on 10:30 p.m. EST.

    Saturday, Dec. 31

  • After the noise and revelry at the turning of midnight, step outside into the silent, cold dark. Sirius shines at its highest due south — a preview of where it will be at dusk when winter nears its end. To its upper right, Orion is just beginning to tilt westward. High to Sirius's upper left shines Procyon. And look high overhead; bright Capella and the Castor-Pollux pair straddle the zenith (if you're at mid-northern latitudes). Lower in the east Mars is glowing yellow-orange, presaging its opposition to come in early March.

    The Moon and Jupiter may look close together, but this is an illusion. Jupiter is currently 1,700 times farther away — and 40 times wider in diameter. (The Moon is positioned here for the middle of North America. For clarity, the Moon is shown three times its actual apparent size.)

    Sunday, Jan. 1

  • First-quarter Moon (exact at 1:15 a.m. on this date Eastern Standard Time). Jupiter is the bright "star" shining left of the Moon early this evening, as shown here.

  • Jupiter's Great Red Spot crosses the planet's central meridian around 9:38 p.m. EST.

    Monday, Jan. 2

  • Jupiter shines about 5° below or lower left of the Moon this evening, as shown here.

  • Algol is at minimum brightness for a couple hours centered on 7:19 p.m. EST.

    Tuesday, Jan. 3

  • Jupiter shines lower right of the Moon, as shown above. Jupiter's Great Red Spot crosses the planet's central meridian around 11:17 p.m. EST.

  • Double shadow on Jupiter. Europa and Ganymede both cast their tiny black shadows on Jupiter from 10:27 to 11:57 p.m. Pacific Standard Time (11:27 p.m. to 12:57 a.m. Mountain Standard Time). Farther east, Jupiter is too low or has set. (For all of Jupiter's satellite events and Great Red Spot transits this month, see "Action at Jupiter" in the January Sky & Telescope, page 52.)

  • Quadrantid meteor shower This should be a fine year for one of the best, but least observed, annual meteor showers. The Quadrantids should be most active in the early morning hours of Wednesday the 4th. The Moon sets around 3 a.m. local time then, leaving the sky dark until the first light of dawn around 6. See our article A Fine Year for the Icy Quads.

    Wednesday, Jan. 4

  • The waxing gibbous Moon shines near the Pleiades tonight.

  • Jupiter's Great Red Spot crosses the planet's central meridian around 7:08 p.m. EST.

  • Earth is at perihelion, its closest to the Sun for the year (just one part in 30 closer than at aphelion in July).

    Thursday, Jan. 5

  • The bright Moon is between the Pleiades and Aldebaran.

    Friday, Jan. 6

  • The Moon tonight shines between the horns of Taurus. The horn tip stars are Beta Tauri, to the Moon's left in early evening for North America, and Zeta Tauri (slightly fainter), to the Moon's lower left.

  • Jupiter's Great Red Spot crosses the planet's central meridian around 8:47 p.m. EST.

    Saturday, Jan. 7

  • The Moon this evening shines in a starry part of the sky. High to its upper left is bright Capella. High to its upper right is Aldebaran. Right or lower right of the Moon, look for Betelgeuse in Orion's shoulder. And farther lower left of the Moon are Pollux and Castor, the heads of the Gemini twins.


    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 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

    Dawn view
    All week, Antares pulls farther away from Mercury in the brightening dawn. Binoculars will help.

    Mercury (magnitude –0.4) appears lower in the dawn every morning. About 45 minutes before your local sunrise, look for Mercury low above the southeast horizon. Don't confuse it with twinkly Antares, which is moving ever farther to Mercury's upper right.

    Venus (magnitude –4.0, in Capricornus) is the brilliant “Evening Star” shining in the southwest during and after twilight. It will continue to move a little higher every week all winter.

    In a telescope, Venus is still just a small gibbous disk 13 arcseconds in diameter; Venus is still on the far side of the Sun, but it's rounding our way.

    Mars (magnitude +0.2, near the hind foot of Leo) rises in the east around 10 p.m., beneath Regulus and the Sickle of Leo. Mars is brightening rapidly now week to week as it approaches Earth. It shines highest in the south around 4 or 5 a.m. In a telescope Mars has grown to 9 arcseconds wide, on its way to 13.9″ at opposition on March 3rd.

    Jupiter (magnitude –2.6, at the Aries-Pisces border) shines very high in the southeast in twilight, due south after nightfall, and moves lower in the southwest as night grows late. It sets in the west around 2 a.m. In a telescope Jupiter appears 43 arcseconds wide; see our observing guide.

    Jupiter on Dec. 29, 2011
    Jupiter's Great Red Spot (GRS) was just about to depart around Jupiter's preceding limb when Christopher Go imaged the planet at 10:56 UT December 29th. South is up. "The wake following the GRS is very active and complex," he writes. "The North Equatorial Belt is very narrow, and the dark red barges are very impressive! Otherwise the northern hemisphere is very quiet."

    Saturn (magnitude +0.7, in Virgo) rises in the east around 1 or 2 a.m. and is high in the south at dawn. Spica, just a little fainter at magnitude +1.0, is 6° to Saturn's right or upper right.

    Uranus (magnitude 5.8, near the Circlet of Pisces) is still high in the south-southwest right after dark.

    Neptune (magnitude 7.9, at the Aquarius-Capricornus border) is getting low in the southwest after dark, more or less in the background of Venus.


    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.


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