Sky at a Glance | February 4th, 2011

Western view after dusk
Watch the Moon pass Jupiter as it waxes from evening to evening. You'll have no trouble spotting them; they're the two brightest objects in the evening sky. (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.)

Friday, February 4

  • Sirius transits the meridian of the sky (i.e. is due south) around 9 or 10 p.m. this week, 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 when Sirius is approaching the meridian. (Canopus transits 20 minutes before Sirius.)

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

  • A dawn challenge! Just before the first light of dawn Saturday morning for your location, get your telescope or binoculars on Venus low in the southeast. Look 3½° south (lower right) of it for the Lagoon Nebula, M8 — a cold winter preview of a summer object. Good luck! Also nearby is the asteroid Vesta, magnitude 7.8. See the article and chart in the February Sky & Telescope, page 57.

    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 above.

    Sunday, February 6

  • Jupiter and the crescent Moon are lined up in the west at dusk, as shown above.

    Monday, February 7

  • The Moon is over Jupiter this evening. Look to their right for the Great Square of Pegasus, tipped onto one corner. (Two of its stars show in the scene above.)

    Tuesday, February 8

  • You may know of the fine winter star cluster M41, visible in binoculars about one binocular field south of Sirius. But what about the cluster M50? Follow a line from Sirius to the tip of Canis Major's nose (Theta Canis Majoris), continue nearly as far exactly straight onward, and there you are. M50 is magnitude 5.9, quite a bit fainter than M41's magnitude 4.5.

    In the same field with M50 is another, the fainter cluster: NGC 2343, a tougher catch at magnitude 6.7. For a finder chart and more about these objects, see Gary Seronik's Binocular Highlight column in the February Sky & Telescope, page 45.

  • Before the start of dawn Wednesday morning, the asteroid Vesta is 0.4° north of Venus. They're magnitudes +7.8 and –4.3, respectively, a 70,000-times difference in brightness!

    Wednesday, February 9

  • The eclipsing binary star Algol (Beta Persei) should be at minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:18 p.m. EST; 7:18 p.m. PST. Algol takes several additional hours to fade and to rebrighten.

    Thursday, February 10

  • First-quarter Moon tonight (exact at 2:18 a.m. Friday morning EST). Look upper left of the Moon for the Pleiades. Farther left of the Pleiades shines Aldebaran.

  • Another dawn challenge! Just before the first light of dawn Friday morning for your location, aim your scope or binoculars at Venus low in the southeast. Look nearly 3° south (lower right) of it for the hazy little glow of the globular cluster M22 (5th magnitude). Upper right of M22, by 7½°, is the larger dim glow of the Lagoon Nebula, M8. Also nearby is the asteroid Vesta, magnitude 7.8. See the article and chart in the February Sky & Telescope, page 57.

    Friday, February 11

  • The Moon shines near the Pleiades after dusk (for the time zones of the Americas). Binoculars give a fine view. Watch the Moon move along its orbit with respect to the cluster as the hours pass.

    Saturday, February 12

  • The Moon shines in Taurus this evening, inside the broad triangle formed by Aldebaran, the Pleiades, and Elnath (Beta Tauri).

  • Algol is at its minimum brightness for a couple hours centered on 7:07 p.m. EST.



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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

    Jupiter on Feb. 11, 2011
    "Jupiter is getting more difficult now," writes imager Christopher Go in the Philippines. But he caught this view of the re-formed South Equatorial Belt (above center) in twilight on February 11th just before Jupiter disappeared behind his building's roof.


    The Great Red Spot is at left. "The SEB is already red in this area and it is also very turbulent," he notes. "The NEB is dark red, and note the dark and white ovals on the NEBn." South is up.


    Mercury, Mars, and Neptune are hidden in the glare of the Sun.

    Venus (magnitude –4.3, in Sagittarius) 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 23° to 30° this week).

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

    Jupiter's Great Red Spot, increasingly hard to see, 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 p.m., but it's best seen in a telescope at its highest in the south in the early-morning hours (Saturn transits around 4 a.m. local time). Don't confuse Saturn with Spica 8° below it during evening, and lower left of it during the morning hours.

    Saturn on Feb. 6, 2011
    Saturn's white spot now "looks like a comet," writes Christopher Go. This extraordinary image exaggerates the marking's contrast, but even visually "it is very distinct" in Go's 11-inch scope. As of March 2nd, the head of the "comet" had moved around to about System III longitude 120°. South is up.


    Click for animation of several images spanning 33 minutes of Saturn's rotation. This one was shot at 18:50 UT Feb. 6, 2011, when the System III central-meridian longitude was 50°.

    Even more awesome Cassini image.


    In a telescope, Saturn's new white spot has spread into a light zone 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 5° west (lower right) of Jupiter and pulling away from it.


    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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