Sky at a Glance | November 18th, 2011

By: Alan MacRobert November 18, 2011 0

Friday, Nov. 25

Action at Jupiter: Tonight Jupiter's icy, enigmatic moon Europa crosses onto the face of the planet at 9:45 p.m. EST, then exits at 12:10 a.m. EST. Europa's tiny black shadow crosses Jupiter from 11:08 p.m. to 1:34 a.m. EST.

New Moon (exact at 1:10 a.m. on this date EST). The Moon partially eclipses the Sun for Antarctica, Tasmania, and small sections of South Africa and New Zealand.

The thin Moon pairs with Venus after sunset on Saturday the 26th. You may need binoculars to pick up Mercury; its visibility low in bright twilight is exaggerated here. (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 its actual size.)

Sky & Telescope diagram

Saturday, Nov. 26

As twilight fades, look low in the southwest for the very thin crescent Moon hanging to the right of Venus, as shown here. During twilight in the Americas, the Moon and Venus are 3° to 5° apart.

Sunday, Nov. 27

Look for Venus shining well to the Moon's lower right in twilight, as shown here. Use binoculars to try a last look for rapidly-fading Mercury, farther down in nearly the same direction.

Monday, Nov. 28

Jupiter's Great Red Spot crosses Jupiter's central meridian around 11:31 p.m. EST (8:31 p.m. PST).

Tuesday, Nov. 29

The thick crescent Moon shines in the southwest after nightfall. Look not far to the Moon's right and lower right for Alpha and Beta Capricorni, respectively. Alpha Cap, yellow, is a wide double star that you may just be able to resolve with your unaided eyes. If not, the smallest binoculars will do the trick.

During dawn, Saturn and Spica remain 5° apart all this week — about half the width of your fist held at arm's length.

Sky & Telescope diagram

Wednesday, Nov. 30

Far to the lower left of the Moon sparkles 1st-magnitude Fomalhaut. It's due south at its highest soon after dark now.

Thursday, Dec. 1

The brightest star in the northeast these evenings is Capella. Look far to its right for Aldebaran in the east, with the dim Hyades stars scattered around it. Above Aldebaran and the Hyades is the smaller but brighter Pleiades cluster.

Friday, Dec. 2

First-quarter Moon (exact at 4:52 a.m. on this date). The Moon, high in the south at dusk, shines below the western side of the Great Square of Pegasus. It's between the Water Jar of Aquarius to its right, and the dimmer Circlet of Pisces to its left.

Mars is at quadrature, 90° west of the Sun in the morning sky. Therefore, Mars is as gibbous as it's going to appear this season (90% lit).

Saturday, Dec. 3

Orion is up! With winter approaching, bright Orion rises into good view in the east-southeast by 8 or 9 p.m. now. In its middle, Orion's three-star Belt is nearly vertical — as is always the case when Orion displays itself in this part of the sky (viewed from mid-northern latitudes).

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 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

With a diameter of just over 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; the north polar region is at bottom. The Solis Lacus area is near top, foreshortened.

Alan MacRobert

Mercury is dropping out of sight deep in the sunset.

Venus (magnitude –3.9) is becoming higher and easier to see in the southwest after sunset. As of this week it finally stays above the horizon until the end of twilight. Venus is on its way up for a grand, high apparition as the "Evening Star" all winter (for the Northern Hemisphere).

Mars (magnitude +0.8, in Leo) rises around 11 or midnight. It's highest in the south by the beginning of dawn. It's near Regulus, which is a little fainter at magnitude +1.3 and slightly blue-white. Mars and Regulus widen from 7° apart on the morning of November 26th to 10° on December 2nd — about a fist-width at arm's length.

In a telescope Mars is a tiny blob only 7 arcseconds wide. Mars is on its way to opposition next March, when it will reach a width of 13.9 arcseconds.

Jupiter on Nov. 26, 2011. South is up. "The North Equatorial Belt is quiet and narrow," writes imager Christopher Go. " Note the small dark spot on the NEBn. The SEB is busy. Note the wide dark band [just] south of the SEB!" The time was 13:12 UT. The System II longitude on the central meridian was 37°.

Christopher Go

Jupiter (magnitude –2.8, at the Aries-Pisces border) blazes high in the east at dusk and highest in the south by late evening. In a telescope Jupiter still appears a big 48 arcseconds wide. See our guide to observing Jupiter with a telescope.

Saturn (magnitude +0.8) is fairly low in the east-southeast as dawn begins, a little higher every morning. Spica (magnitude +1.0) sparkles 4° to its right. Brighter Arcturus shines far to their left or upper left.

Uranus (magnitude 5.8, near the Circlet of Pisces) and Neptune (magnitude 7.9, at the Aquarius-Capricornus border) are well placed in the southern sky early in the evening. 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 Standard Time (EST) equals Universal Time (also known as UT, UTC, or GMT) minus 5 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. You know you want it for the holidays....

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