Sky at a Glance | February 19th, 2010

Some daily events in the changing sky for February 19 – 27.

Friday, February 19

  • After dark, look just to the right of the Moon for the stars of Aries. Look much higher to the Moon's upper left for the Pleiades.

    Having just threaded between Gamma and 40 Leonis, 6th-magnitude Vesta is now crossing the interior of Leo's Sickle. Click on the map for a full-page printable PDF version. (The tick marks are for 0 hours Universal Time on the dates indicated; this falls on the evening of the previous date in the time zones of the Americas.)
    Tony Flanders
  • The bright asteroid 4 Vesta, just past opposition and still magnitude 6.1, continues its travels across the Sickle of Leo, as shown here. Spot it in binoculars; see our article.

    Saturday, February 20

  • The Pleiades sparkle above the Moon this evening. Off to their left is the Hyades cluster — much larger, looser, and dimmer, but highlighted by bright orange Aldebaran.

    Sunday, February 21

  • First-quarter Moon (exact at 7:42 p.m. Eastern Standard Time).

    Monday, February 22

  • A small telescope will always show Titan, Saturn's largest satellite. Tonight Titan is four ring-lengths to Saturn's east. A 6-inch telescope will begin to show the orange color of its smoggy atmosphere.

    Tuesday, February 23

  • At this time of year, Orion stands at his highest in the south after dusk. His top-left star is bright, orange-red Betelgeuse. It forms the Winter Triangle (almost equilateral) with Procyon to its left and bright white Sirius below them both.

    Wednesday, February 24

  • Castor and Pollux are left of the Moon during the evening, as shown below.

    Watch the waxing gibbous Moon pass Castor and Pollux, then Mars, then Regulus. (This view 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. In the Far East, move it halfway. For clarity, the Moon is shown three times actual size.)

    Thursday, February 25

  • The bright, fiery "star" near the gibbous Moon tonight is Mars, as shown above. A telescope reveals that Mars too is becoming gibbous; it's now nearly a month past opposition.

    Friday, February 26

  • The Moon, Mars, Pollux, and Castor form a long, ragged line this evening, as shown above.

    Saturday, February 27

  • The "star" over the Moon this evening is Regulus, as seen above.


    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'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 lost in the glow of sunrise.

    Venus (magnitude –3.9) is barely emerging from deep in the sunset. Look for it just above the west-southwest horizon about 20 minutes after sundown. Binoculars help.

    Mars at 3:25 UT Feb. 12, 2010
    Mars's north polar cap (bottom) was bright again, and clouds showed on the planet's east, west, and south limbs, when Don Parker of Coral Gables, Florida, took this image on the evening of February 11th (at 3:25 February 12th Universal Time). At left is dark Syrtis Major; just above center is long Sinus Sabaeus; and upper right of center is Sinus Meridiani. The central meridian longitude was 335°. Click on the image for larger views and more information.


    Parker used a 16-inch Newtonian reflector and a Skynyx 2-0 camera. Stacked-video imagery like this can show detail on a planet much more clearly than the eye can see through the same telescope.

    Donald C. Parker

    Mars, still bright at magnitude –0.8, shines high in the east at dusk and is highest in the south around 10 p.m. It's in Cancer, below Pollux and Castor after dark.

    In a telescope Mars is shrinking: from 13.0 to 12.4 arcseconds wide this week. Its north polar cap is again bright, but watch for it shrinking in the Martian northern-hemisphere spring during the coming weeks. Identify other surface features you see using the Mars map and observing guide in the December Sky & Telescope, page 57.

    Jupiter is hidden behind the glare of the Sun.

    Saturn (magnitude +0.6, in western Virgo) rises in the east around 8 p.m. and stands highest in the south around 1 or 2 a.m. In a telescope, Saturn's rings are tilted only 4.1° from edge-on to us, and they'll narrow further in the coming months.

    Uranus and Neptune are behind the glare of the Sun.

    Pluto is low in the southeast before dawn.

    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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