Sky at a Glance | January 28th, 2011

Dawn view
Early risers can watch the waning Moon pass bright Venus, with Antares and Scorpius looking on. (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. The blue 10° scale is about the size of your fist held at arm's length.)

Friday, January 28

  • During dawn Saturday morning, the waning crescent Moon shines with bright Venus to its left, as shown above.

  • Is your sky dark enough for you to see the Great Andromeda Galaxy? It's just off the knee of the Andromeda stick figure. The brighter, sharper bottom-point of the Cassiopeia W points to it.

  • Jupiter's Great Red Spot transits Jupiter's central meridian around 8:23 p.m. Central Standard Time.

    Saturday, January 29

  • As winter advances, the Big Dipper is working its way upward toward dominating the high sky of spring. Already the Dipper is standing on its handle in fine view in the northeast after dinnertime.

  • During dawn Sunday morning, the thin waning Moon is below Venus, as shown above.

    Sunday, January 30

  • Orion stands high in the southeast after dinnertime this week, with his diagonal belt pointing down toward brilliant Sirius.

  • Jupiter's Great Red Spot transits the planet's central meridian around 8:02 p.m. Pacific Standard Time.

    Bright sky shortly before sunrise. Use binoculars!
    Use Venus as your starting point to try for Mercury and the very old Moon just above the southeast horizon about 15 minutes before sunrise. Mercury and Venus are 30° apart. The farther south you are, the better your chances.

    Monday, January 31

  • About 15 minutes before your local sunrise time Tuesday morning, use binoculars to scan just above the southeast horizon, far lower left of Venus, for the very thin crescent Moon with Mercury below it — as shown here.

    Tuesday, February 1

  • As the stars come out in late twilight this week, the Northern Cross of Cygnus plants itself upright on the northwest horizon (as seen from the world's mid-northern latitudes).

    Wednesday, February 2

  • Bright Capella passes overhead between 7 and 9 p.m., depending on how far east or west you live in your time zone. How close Capella passes to your zenith depends on how far north or south you live. It goes exactly through your zenith if you're at latitude 46° north (Seattle; Montreal; central France).

  • New Moon (exact at 9:31 p.m. Eastern Standard Time).

  • Jupiter's Great Red Spot transits around 8:33 p.m. Eastern Standard Time.

    Thursday, February 3

  • Sign of the times: With the coming of February, as early as 9 or 10 p.m. the Big Dipper climbs to the same height in the northeast as Cassiopeia has descended in the northwest.

    And look midway between them for Polaris, the North Star.

  • Europa transits Jupiter's face from 5:28 to 8:12 p.m. Pacific Standard Time. Europa's shadow follows across Jupiter almost exactly two hours behind.

    Friday, February 4

  • Sirius transits the meridian of the sky (i.e. is due south) around 9 or 10 p.m. now, depending on where you live east or west in your time zone. Sirius is the brightest star in all the sky (after the Sun). The second brightest is far-southern Canopus. By coincidence, Canopus and Sirius transit at nearly the same time. If you live at least as far south as Atlanta, Phoenix, or Los Angeles, see if you can spot Canopus just above the south point on your horizon just 20 minutes before Sirius is due south.

  • Jupiter's Great Red Spot crosses the planet's central meridian around 7:12 p.m. Pacific Standard Time.

    Western view after dusk
    Back in the evening sky, the waxing Moon passes Jupiter. (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.)

    Saturday, February 5

  • Jupiter and the waxing crescent Moon inhabit the western sky during twilight and early evening tonight and for the next few nights, as shown here.



    Sky at a Glance is now an iPhone app! Put S&T SkyWeek on your iPhone, iPad, or iPod Touch and get these listings anytime, anywhere — with interactive sky maps! Tap a button to see the scene described, customized for your location worldwide. From there you can scroll the view all around the sky, zoom in or out, change to any time or date, and turn on animation. Now also includes This Week's Planet Roundup (below).

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    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
    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 Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger and deeper 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 Sky Atlas 2000.0 Companion by Strong and Sinnott, or the more detailed and descriptive 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

    Mercury is lost deep in the glow of sunrise.

    Venus (magnitude –4.3) blazes as the "Morning Star" in the southeast before and during dawn. Look also for Antares, 150 times fainter at magnitude +1.1, well to Venus's right or upper right (by 15° to 23° this week).

    Mars is hidden in the glare of the Sun and will remain so all winter and spring.

    Jupiter (magnitude –2.2, in Pisces) shines brightly in the southwest as the stars come out; it sinks lower later. Jupiter sets around 9 or 10 p.m. now. Get your telescope on it right at dusk when it's still high. Jupiter has shrunk to only 36 or 35 arcseconds wide, but keep watch on Jupiter's South Equatorial Belt re-forming.

    Jupiter's Great Red Spot is near System II longitude 157°. Assuming it stays there, here are all of the Great Red Spot's predicted transit times until Jupiter disappears for the season.

    Saturn (magnitude +0.6, in Virgo) rises around 10 or 11 p.m.. but it's best seen in a telescope at its highest in the south in the hours before dawn. Don't confuse Saturn with Spica 8° below or lower left of it.

    In a telescope, Saturn's big new white spot has spread in longitude to form a bright band far around the planet. Saturn's rings are 10° from edge on, their maximum for this year. And see how many of Saturn's satellites you can identify in your scope using our Saturn's Moons tracker.

    Uranus (magnitude 5.9) is about 4° west of Jupiter and pulling away from it.

    Neptune (magnitude 7.9, at the Capricornus-Aquarius border) is disappearing into the sunset.


    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.


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