Sky at a Glance | October 28th, 2011

Half hour after sunset
Day by day, Venus and Mercury are becoming a little easier to see low after sunset. The visibility of objects in bright twilight is exaggerated here.

Friday, Oct. 28

  • In bright twilight, look for the thin crescent Moon very low in the southwest. Can you spot Venus to its lower right, as shown here? They're separated by roughly a fist-width at arm's length (depending on your longitude). Use binoculars to try for much fainter Antares and Mercury.

  • Jupiter is at opposition tonight, opposite the Sun as seen from Earth. This an unusually close opposition of Jupiter, one of the closest in its 12-year cycle.

    Saturday, Oct. 29

  • The crescent Moon is higher and easier to spot now after sunset. Its round side points to the lower right, toward very low Venus and Mercury.

    Sunday, Oct. 30

  • Comet Garradd continues glowing at 6th magnitude just as predicted. Find it with binoculars or a telescope near the head of Hercules in the western sky right after dark, using our finder chart online or in the November Sky & Telescope, page 52.

  • If you're in the Eastern time zone, you'll find Algol at its minimum brightness at nightfall. Farther west, Algol will already be rebrightening when the sky gets dark.

    Dawn view
    Binoculars will help pull Saturn and Spica out of the bright dawn all week.

    Monday, Oct. 31

  • Halloween evening finds the crescent Moon lowering in the southwest and bright Jupiter rising higher in the east. Perfect for setting up your telescope in the driveway and giving looks to visiting trick-or-treaters! In this way are new astronomers sometimes made.

    Tuesday, Nov. 1

  • Face west after dark and look very high for Vega, the brightest star there. Even higher above it, near the zenith, is Deneb. Farther to Vega's left or lower left shines Altair. These three stars form the increasingly misnamed Summer Triangle.

    Wednesday, Nov. 2

  • First-quarter Moon (exact at 12:38 p.m.). The half-lit Moon stands high in the south at sunset. As the stars come out, the Moon reveals itself to be above the dim star-pattern of Capricornus.

    Thursday, Nov. 3

  • Look lower left of the Moon this evening, by two or three fist-widths at arm's length, for Fomalhaut, the Autumn Star.

    Friday, Nov. 4

  • Jupiter's moon Io disappears behind Jupiter's western limb tonight around 10:24 p.m. Eastern Daylight Time. Then it reappears out of eclipse from Jupiter's shadow, just barely off the planet's eastern limb, around 12:44 a.m. EDT. At almost that same minute, Jupiter's Great Red Spot should be crossing the planet's central meridian.

    For timetables of all of Jupiter's Red Spot transits and satellite events this month, good worldwide, see the November Sky & Telescope, page 54.

    Saturday, Nov. 5

  • Look upper left of the Moon this evening for the Great Square of Pegasus, tipped up on one corner.

  • Daylight-saving time ends (for most of North America) at 2 a.m. Sunday morning. Clocks "fall back" an hour.


    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
    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 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 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

    Mars on Nov. 2, 2011
    With a diameter of only 6 arcseconds, Mars still isn't much to look at in a telescope. But stacked-video imaging can work wonders. On the morning of November 2nd, Sky & Telescope's imaging editor Sean Walker assembled this shot using a 12.5-inch Newtonian reflector at f/44, a DMK 21AU618.AS video camera, and Astrodon RGB filters.


    South is up; note the north polar region at bottom. The Solis Lacus area is near top, foreshortened.

    Alan MacRobert

    Mercury and Venus (magnitudes
    –0.3 and –3.8, respectively) are close together just above the southwest horizon in bright twilight all week. Venus is on top; much fainter Mercury is 2° below it. Binoculars help. Binoculars may also show fainter, twinkly Antares much farther to their left or upper left, as shown here.

    Mars (magnitude +1.1, in Leo) rises around 1 or 2 a.m. daylight-saving time. By the beginning of dawn it's in good view high in the east-southeast. Mars is closing in on similarly bright Regulus below it. They're 7° apart on October 29nd and 4° apart by November 5th. About 10° to their left shines Gamma Leonis, not much fainter, making a nice triangle with them. In a telescope, Mars is a tiny blob only 6 arcseconds wide.

    Jupiter (magnitude –2.9, in southern Aries) blazes brightly at opposition. It's low in the east-northeast in twilight, higher in the east to southeast all evening, and highest in the south around the middle of the night.

    Jupiter on Nov. 1, 2011
    Jupiter was a big 49.6 arcseconds wide when S&T's Sean Walker took this image on the evening of November 1st. South is to the upper right. The reddish South Equatorial Belt remains wider (and bicolored) compared to the North Equatorial Belt. Walker used the same imaging setup as for Mars above.
    S&T: Sean Walker

    Moreover, this is an unusually close Jupiter opposition. Last year Jupiter came closer to Earth than it had since 1963, and this year it's only an insignificant 0.4% farther. It appears 49.6 arcseconds wide. See our guide to observing Jupiter with a telescope.

    Saturn (magnitude +0.7) is very low in the east-southeast as dawn brightens, becoming a little easier to see above the horizon each morning. Look for sparkly Spica 5° to its lower right all week, as shown here.

    Uranus (magnitude 5.7, in Pisces) and Neptune (magnitude 7.9, in Aquarius) are well placed in the south and southeast after dinnertime. Use our printable finder chart for both, or see the September Sky & Telescope, page 53.


    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 Daylight Time (EDT) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.


    NEW BOOK: Sue French's DEEP-SKY WONDERS! This big, long-awaited observing guide by Sky & Telescope's Sue French is now available from Shop at Sky. Hefty and lavishly illustrated, it contains Sue’s 100 favorite sky tours (25 per season, with finder charts) from her 11 years of writing the Celestial Sampler and Deep-Sky Wonders columns for S&T. Don’t miss it!


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