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This Week's Sky at a Glance

by Alan M. MacRobert

Some daily events in the changing sky for November 20 – 28.

Watch the waxing Moon creep up on Jupiter from night to night. (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. The blue 10° scale is about the size of your fist held at arm's length.)
Sky & Telescope diagram
Friday, November 20

  • Asteroid occultation. Tonight the faint asteroid 234 Barbara occults a 7.5-magnitude star west of Procyon as seen from parts of central Florida, the southern UK, northern Germany, and Russia. Finder charts, times, and other information. Scotty Degenhardt is coordinating the timing campaign in Florida; see his web page for this event.

  • Jupiter's Great Red Spot should cross Jupiter's central meridian around 6:14 p.m. Pacific Standard Time. The "red" spot is pale orange-tan, so a light blue or green filter helps improve its contrast. The Red Spot transits about every 9 hours 56 minutes; for all of the Red Spot's central-meridian crossing times, good worldwide, use our Red Spot calculator or our list for the rest of 2009.

  • Starting a little later, Jupiter's biggest moon, Ganymede, casts its tiny black shadow onto Jupiter's face: from 7:03 to 10:37 p.m. Pacific Standard Time.

    Saturday, November 21

  • In the western twilight, the crescent Moon shines about two fist-widths to the lower right of Jupiter, as shown above.

    Sunday, November 22

  • Jupiter shines left of the Moon this evening, as shown above. Look right of the Moon for Alpha and Beta Capricorni. Alpha is a naked-eye double star for the sharp-eyed. Beta is also a wide double, but here the secondary star is dim enough (magnitude 6.2) that you'll need binoculars.

  • Jupiter's Red Spot transits around 7:53 p.m. Pacific Standard Time.

    Monday, November 23

  • Jupiter shines just below the Moon this evening.

  • Watch in a telescope as Jupiter's moon Ganymede occults Europa from 7:31 to 7:40 p.m. EST. They'll appear to merge and then separate as the minutes before and after tick by. For a complete list of such mutual events among Jupiter's satellites visible from North America through the end of the year, see the October Sky & Telescope, page 56.

  • An hour later, watch Jupiter's moon Europa reappear from eclipse out of Jupiter's shadow, just east of the planet, at 8:41 p.m. EST.

    Tuesday, November 24

  • First-quarter Moon (exact at 4:39 p.m. EST).

  • Jupiter's moon Io occults Europa from 8:19 to 8:24 p.m. EST.

    Wednesday, November 25

  • Jupiter's Red Spot transits around 8:23 p.m. Eastern Standard Time.

    Thursday, November 26

  • The Moon shines high in the south after dinnertime. Look above it for the Great Square of Pegasus. Your fist at arm's length will fit inside the Square.

    Friday, November 27

  • Jupiter's moon Io casts its shadow onto Jupiter's face from 7:36 to 9:52 p.m. EST.

  • Jupiter's Red Spot transits around 7:03 p.m. Pacific Standard Time.

    Saturday, November 28

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




    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).

    Pocket Sky Atlas
    The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but that's less than one star in an entire telescopic field of view, on average. By comparison, Sky Atlas 2000.0 plots 81,312 stars to magnitude 8.5, typically one or two stars per telescopic field. Both atlases include many hundreds of deep-sky targets — galaxies, star clusters, and nebulae — to hunt among the stars.
    Sky & Telescope
    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

    Mercury is hiding deep in the sunset.

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

    Mars on Nov. 18, 2009
    On November 18th, when Sky & Telescope's Sean Walker took this stacked-video image, Mars had grown to 9.0 arcseconds in diameter. The most obvious features are the North Polar Cap and Cloud Hood at bottom, its dark "collar," and the Solis Lacus complex at top. "Good seeing this morning," writes Walker. "Note the bright cloud in Arcadia [just above the North Polar Cap collar]; the yellowish color is intriguing; could it be a small dust storm?"
    S&T: Sean Walker
    Mars (magnitude +0.1, in Cancer) rises as early as 10 p.m. now, far below Castor and Pollux in the east. It's very high in the south before dawn. In a telescope Mars is 9 arcseconds wide and growing. Can you make out its north polar cap, bordered by a dark polar-cap 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 in twilight, and lower in the southwest later in the evening. It sets around 10 p.m.

    Saturn (magnitude +1.0, in the head of Virgo) shines in the southeast before and during dawn. In a telescope, its rings are still 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 4° east of Jupiter. Use our finder charts for Uranus and Neptune.

    Pluto is lost in the sunset.

    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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