Sky at a Glance | November 30th, 2012

Dawn view
Mercury has emerged into fine view low in early dawn, lining up with Venus and Saturn. Watch all week as the line lenghtens; Saturn (and Spica) move higher to the upper right. The blue 10° scale is about the width of your fist at arm's length.

Friday, November 30

  • The waning Moon rises less than an hour after the end of twilight. Once it's up, look to the right of it (by a bit more than a fist-width at arm's length) for orange-red Betelgeuse sparkling in Orion's rising shoulder.

    Saturday, December 1

  • Since Jupiter just about at opposition, the asteroids Ceres and Vesta in Jupiter's vicinity are near opposition too. Vesta has brightened to magnitude 6.6, Ceres 7.2. Spot them in binoculars using our finder chart in the December Sky & Telescope, page 50, or online. They're near the horns of Taurus. This evening you'll have the darkest view of them shortly before moonrise. (The Moon rises around 7 p.m. depending on your location.)

    Sunday, December 2

  • Jupiter is at opposition tonight: opposite the Sun as seen from Earth. So it rises around sunset, shines highest in the south around midnight, and sets around sunrise. Whenever Jupiter comes to opposition at this time of year, it's shining near Aldebaran and the Pleiades.

    Majestic Orion
    Orion on the rise stands framed between treetops at the start of a cold winter night in Wyoming’s Teton Mountains. First-quarter moonlight illuminates the scene. Centered between the trees is Orion’s three-star Belt, nearly vertical. Sirius has not yet risen.
    Allan E. Morton

    Monday, December 3

  • By 8 or 9 p.m., wintry Orion is well up in the east-southeast. Orion's Belt in his middle points up more or less toward Aldebaran and bright Jupiter. And it points down toward where Sirius, the brightest star of the night, is about to rise. Watch for it.

    Tuesday, December 4

  • Sometime between 6 and 8 each evening now (depending on how far east or west you live in your time zone), bright Vega sinking in the northwest, and equally bright Capella climbing in the northeast, will be at exactly the same height. How accurately can you time their balance moment for your location?

    Wednesday, December 5

  • Ganymede, the largest satellite of Jupiter, crosses Jupiter's face tonight from 9:25 to 11:17 p.m. EST, closely followed by its black shadow from 9:37 to 11:44 p.m. EST. In amateur telescopes, Ganymede's shadow will be much more obvious against Jupiter's bright surface than Ganymede itself is.

    Thursday, December 6

  • Last-quarter Moon (exact at 10:31 a.m). The Moon rises around the middle of the night tonight. In the small hours of Friday morning it climbs the eastern sky beneath Leo.

  • Jupiter's Great Red Spot crosses Jupiter's central meridian around 11:45 p.m. EST. (For all of Jupiter's satellite events and Great Red Spot transit times this month, good worldwide, see the December Sky & Telescope, pages 51–52.)

    Friday, December 7

  • This is the time of year when the Andromeda Galaxy, M31, passes the zenith in early evening for skywatchers at mid-northern latitudes. It goes exactly through your zenith if you're at 41° north latitude (New York, Denver). When this happens depends on your location.

    Saturday, December 8

  • This is the time of year when Cassiopeia, now a flattened M shape, is poised at its very highest in the north in early evening.

  • Vesta is at is opposition tonight, not far from Jupiter. It's magnitude 6.4. Ceres, which comes to opposition in nine days, is magnitude 6.9. Spot them in binoculars using our finder chart in the December Sky & Telescope, page 50, or online.


    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 guide to 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 with a telescope effectively.

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

    Can a computerized telescope replace charts? Not for beginners, I don't think, and certainly not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability). As Terence Dickinson and Alan Dyer say in their invaluable 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, Venus, and Saturn form a diagonal line in the southeast when dawn begins to brighten, as shown at the top of this page. Venus is by far the brightest at magnitude –3.9. Look upper right of it for distant Saturn, magnitude +0.7. Look lower left of Venus for Mercury, magnitude –0.5. Mercury is having an excellent apparition through the first half of December. This diagonal line of three lengthens from 13° to 19° long this week.

    Added bonus: Look upper right of the planet lineup for Spica, similar to Saturn at magnitude +1.0.

    Mars (magnitude +1.2, in Sagittarius) remains low in the southwest in evening twilight. In a telescope it's just a tiny blob 4.4 arcseconds in diameter.

    Jupiter at 3:33 UT Nov. 23, 2012
    The Great Red Spot's side of Jupiter is busy indeed. Sky & Telescope imaging editor Sean Walker shot this image with his 12.5-inch Newtonian reflector and DMK21AU618 planetary video camera on November 22nd. South is up. From upper left, note the orange ring of Oval BA, the tiny dark-red dot following it, the Great Red Spot in its white Red Spot Hollow, and the huge turbulence behind it roiling the South Equatorial Belt.


    The South Temperate Belt is barely visible along some of its length but prominent on the following side of the Great Red Spot. Four white ovals dot the South South Temperate Belt. On the north side of the planet, the North Equatorial and North Temperate belts have become cleanly separated by the North Tropical Zone's return to whiteness. Blue festoons intrude into the bright Equatorial Zone. The satellite to the left is sulfur-colored Io.

    S&T: Sean Walker

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    Jupiter (magnitude –2.8, in Taurus) is at opposition this week (opposite the Sun as seen from Earth). It rises around sunset, climbs the eastern sky in the evening, shines highest in the south around midnight, and sets in the west around sunrise. Orange Aldebaran is 5° to its lower right during evening. Above them are the Pleiades. In a telescope, Jupiter is big 48 arcseconds wide, essentially as large as ever appears.

    Uranus (magnitude 5.8, in Pisces) and Neptune (7.9, in Aquarius) are conveniently placed in the south right after dark. Finder charts for Uranus and Neptune.


    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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