Sky at a Glance | November 30th, 2007

Some daily events in the changing sky for November 30 – December 8.

Comet Holmes and Moon on Nov. 21, 2007
The head of Comet Holmes was about 0.6° wide, just a bit larger than the Moon, on November 21st as shown in this pair of images that Gary Seronik shot at the same scale. The comet has continued swelling since then. Click image for larger view.
S&T: Gary Seronik
Comet Holmes is once again easy to spot with the unaided eye, now that the evening sky is moonless again. It continues fading gradually, but it's big. Look for it a bit above Alpha Persei. Binoculars give a beautiful view. See our recent update with finder chart, full story, and reader photos.

And don't look now, but another comet is on the way in! Comet 8P/Tuttle is still only 9th magnitude, but it should brighten to 6th magnitude from late December through mid-January. And while Comet Holmes stays stuck in Perseus for months, Comet Tuttle (being much nearer) will dive from the north celestial pole all the away across the evening sky and below the southern horizon during the same time. See the article and charts in the January Sky & Telescope, page 73.

Friday, November 30

  • The bright eclipsing variable star Algol, Beta Persei — a neighbor of Comet Holmes — should be in one of its periodic dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:14 p.m. Eastern Standard Time. Algol takes several additional hours to fade and to rebrighten.

    Catch the Moon carrying on with Saturn on the morning December begins. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. For clarity, the Moon is shown three times actual size.)
    Sky & Telescope diagram
  • Before and during dawn Saturday morning, look for Saturn just above the last-quarter Moon, as shown here.

    Saturday, December 1

  • Last-quarter Moon (exact at 7:44 a.m. Eastern Standard Time).

    Sunday, December 2

  • Mars is passing less than ½° north of the 3rd-magnitude star Epsilon Geminorum, which is only 2% as bright.

    Monday, December 3

  • Algol should be at minimum light for a couple hours centered on 6:03 p.m. EST. Watch it brighten during the night.

    Tuesday, December 4

  • Before and during dawn Wednesday morning, the waning crescent Moon forms a narrow triangle with bright Venus to its left and much fainter Spica closer above it. See the illustration below.

    Wednesday, December 5

  • If you have a fairly large telescope and are really ambitious — or have a planetary-imaging setup — you can try to catch the tiny moons of Mars, Phobos and Deimos, on any good night this month. Use our interactive locator to find where they ought to be at the date and time you observe.

    Thursday, December 6

  • During dawn this morning and tomorrow morning, Venus guides the way to the waning Moon far beneath it, as shown below.

    Friday, December 7

  • The red long-period variable star T Cephei, one of the brightest in the sky, should be at its peak of about magnitude 6.0 this week. See the article and finder chart in the December Sky & Telescope, page 78.

    Saturday, December 8

  • Sky tip: Mars and Orion rise in the east around the same time in early evening and shine at the same height for several hours thereafter. Look for Orion to the right of brilliant Mars by two or three fist-widths at arm's length.

    Looking southeast in early dawn
    Watch the waning Moon pass Venus and Spica in the chilly December dawn.
    Sky & Telescope diagram

    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 foldout map in 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 maps; the standard is Sky Atlas 2000.0) and good deep-sky guidebooks (such as Sky Atlas 2000.0 Companion by Strong and Sinnott, the even more detailed Night Sky Observer's Guide by Kepple and Sanner, or the enchanting though increasingly dated Burnham's Celestial Handbook). Read how to use them effectively.

    More beginners' tips: "How to Start Right in Astronomy".

    This Week's Planet Roundup

    Mercury is lost in the glow of sunrise. During its recent fine morning apparition, John Boudreau of Saugus, Massachusetts, shot perhaps the best amateur imagery of Mercury we've ever seen.

    Venus (magnitude –4.2, in Virgo) is the bright "Morning Star" blazing in the southeast before and during dawn. Spica, much dimmer, shines within a few degrees of it.

    Mars on Nov. 19, 2007
    Syrtis Major juts upward in this image of Mars taken by S&T's Sean Walker on the morning of November 19th. The huge North Polar Hood of clouds was thin enough that surface features showed through. And note the bright haze filling the Hellas Basin, near the limb at the 7 o'clock position. Mars was 14 arcseconds wide, and the central-meridian longitude was 269°. Walker used a 12.5-inch reflector, a DMK 21AF04.AS camera, and CS RGB color filters.
    S&T: Sean Walker
    Mars, shining bright yellow-orange (magnitude –1.3) in Gemini, now rises as early as 6 or 7 p.m. and is high up in fine view in the east by 9 or 10. It shines very high in the early-morning hours — passing near the zenith, in fact, for observers at mid-northern latitudes (around 2 a.m.).

    In a telescope Mars now appears 15 arcseconds in diameter, almost as wide as the 15.9" it will display when nearest Earth on the night of December 18th. For all about observing Mars with a telescope this season, see the guide and surface-feature map in the November Sky & Telescope, page 66.

    Jupiter (magnitude –1.8) is disappearing into the sunset. Can you still catch it just above the southwest horizon in bright twilight? Bring binoculars.

    Saturn (magnitude +0.7) rises by about midnight and is very high in the south before dawn. Fainter Regulus (magnitude +1.4) is 8° to Saturn's upper right after they rise, and directly right of it as they fade out in dawn's glow.

    Uranus (magnitude 5.8, in Aquarius) is still well placed in the south right after dark, high above Fomalhaut.

    Neptune (magnitude 7.9, in Capricornus) is getting lower in the southwest. Finder charts for Uranus and Neptune are in the July Sky & Telescope, page 60, and online.

    All descriptions that relate to your horizon or zenith — including the words up, down, right, and left — are written for the world's midnorthern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America. Eastern Standard Time (EST) equals Universal Time (UT, UTC, or GMT) minus 5 hours.

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