Some daily events in the changing sky for November 27 – December 5.

As the Moon wanes away from full, watch it descend the late-evening sky on its way to meeting Mars. (This scene is 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.)

Sky & Telescope diagram

Friday, November 27

  • Soon after dark this week, look lower left of Jupiter for Fomalhaut, and farther to Jupiter's right for Altair.

    Saturday, November 28

  • Look left of the waxing gibbous Moon this evening for the stars of the little constellation Aries.

    Sunday, November 29

  • Jupiter's Red Spot transits the planet's central meridian around 8:42 p.m. Pacific Standard Time.

    Monday, November 30

  • Jupiter's Red Spot transits the planet's central meridian around 7:33 p.m. Eastern Standard Time.
  • The tiny black shadow of Jupiter's moon Europa crosses Jupiter's face from 8:26 to 11:18 p.m. EST.

    Tuesday, December 1

  • Full Moon tonight (exact at 2:30 a.m. Wednesday morning EST).
  • Even though it's December, the Summer Triangle is still high in the west after dark. The brightest of its three stars is Vega in the west-northwest. Deneb is the brightest star above Vega. Altair shines farther to Vega's left.
  • Jupiter's moon Ganymede slowly emerges from eclipse out of Jupiter's shadow, a little east of the planet, around 7:32 p.m. EST. For a list of all such Jupiter-satellite phenomena this month, good worldwide, see the December Sky & Telescope, page 47.

    Wednesday, December 2

  • The bright Moon shines between the horntips of Taurus this evening.
  • Jupiter's Red Spot transits the planet's central meridian around 6:13 p.m. Pacific Standard Time.
  • Almost at the same time, Jupiter's moon Io occults Europa: from 6:09 to 6:13 p.m. Pacific Standard Time. Watch them merge and separate during the minutes before and after!

    Algol Star Map

    Algol (Beta Persei) was the first eclipsing variable star discovered. Good comparison stars are Gamma Andromedae to Algol's west, magnitude 2.1, and Epsilon Persei to its east, magnitude 2.9. Click chart for larger view.

    Thursday, December 3

  • The bright eclipsing variable star Algol should be in one of its periodic dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:51 p.m. EST. Algol takes several additional hours to fade and to rebrighten. Use the comparison-star chart at right.

    (The minima-of-Algol times printed in the December S&T are incorrect. Use the times for December that are printed in the January issue, page 62.)

    Friday, December 4

  • Earliest end of twilight for the year (at latitude 40° north). The earliest sunset at that latitude comes three days later, on December 7th.
  • The waning gibbous Moon shines between Procyon, to its lower right, and Pollux and Castor, to its upper left, as shown at the top of this page.
  • Jupiter's moon Io casts its tiny shadow onto Jupiter from 6:31 to 8:48 p.m. Pacific Standard Time.

    Saturday, December 5

  • Once the Moon us well up in the east late this evening, look lower left of it for bright Mars, as shown at the top of this page. By dawn Sunday morning they're very high, with Mars now to the Moon's upper left.
  • Jupiter's moon Io reappears out of eclipse from Jupiter's shadow at 8:57 p.m. EST. A small telescope will show it gradually swelling into view just east of the planet.

    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 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 and a curious mind." Without these, "the sky never becomes a friendly place."

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

    This Week's Planet Roundup

    Jupiter is getting smaller week by week as Earth pulls farther ahead of it in our orbit around the Sun. These images were taken by Christopher Go on November 29th. In the top image, the Great Red Spot is just about to rotate off the preceding (celestial western) limb. By the time of Go's second image, 1 hour 16 minutes later, Jupiter was lower in the sky and the seeing was much worse.

    Note the four small, dark red spots following the Great Red Spot at nearly the same latitude. (The fourth is seen best in the bottom image, after Jupiter had rotated substantially.)

    South is up. The South Equatorial Belt has faded greatly compared to the darker North Equatorial Belt. And its north and south components are now different colors!

    Stacked-video images like these usually show much more detail than a planet will show to the eye through the same telescope.

    Christopher Go

    Mercury is hiding deep in the sunset.

    Venus (magnitude –3.9) is disappearing very low in the dawn. Look for it just above the east-southeast horizon 20 or 30 minutes before your local sunrise time.

    Mars (magnitude 0.0, in easternmost Leo) rises around 9 or 10 p.m. local time, far below Castor and Pollux a bit north of east. It's very high in the south before dawn. In a telescope Mars is 10 arcseconds wide and growing. The planet's north polar cap is in good view this season, currently bordered by a wide, dark collar. Any other surface features? Clouds? See the Mars map and observing guide in the December Sky & Telescope, page 57. Mars is on its way to opposition late next January, when it will be 14.1 arcseconds wide.

    Jupiter (magnitude –2.3, in Capricornus) shines brightly in the south-southwest in late twilight, and lower in the southwest later. It sets around 10 p.m. local time.

    Saturn (magnitude +1.0, in the head of Virgo) rises around 1 or 2 a.m. and shines in the southeast before and during dawn. Its rings are still narrow, tilted only 4° from edge-on.

    Uranus (magnitude 5.8, below the Circlet of Pisces) is highest in the south during early evening.

    Neptune (magnitude 7.9, in Capricornus) lurks 3° east of Jupiter, which shines 12,000 times brighter. Nevertheless Neptune is detectable in good binoculars. Use our finder charts for both Uranus and Neptune.

    Pluto is hidden behind the glare of the Sun.

    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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