Some daily events in the changing sky for February 26 – March 6.

Friday, February 26

  • The Castor, Pollux, Mars, the Moon, and Regulus form a long, ragged line high in the sky this evening, as shown below.

    Saturday, February 27

  • The "star" over the Moon this evening is Regulus, as seen above.
  • The bright eclipsing variable star Algol should be in one of its periodic dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 11:31 p.m. EST (8:31 p.m. PST). Algol takes several additional hours to fade and to rebrighten. Use our comparison-star chart. (For all times of Algol's minima this month, good worldwide, see the March Sky & Telescope, page 56.)

    Sunday, February 28

  • Full Moon (exact at 11:38 a.m. today EST).

    Monday, March 1

  • This evening Saturn shines left of the great big rising Moon, which is just past full and just past perigee. By dawn Tuesday morning they've shifted way over to the west-southwest, and Saturn has turned to the Moon's upper right, as shown below.

    Dawn view

    Early risers can follow the waning Moon passing under Saturn and Spica in early dawn.

    Sky & Telescope diagram

  • Saturn's large moon Titan is three or four ring-lengths west of Saturn tonight through Wednesday night. A guide to identifying other Saturnian satellites that are often visible in amateur scopes is in the March Sky & Telescope, page 47.

    Tuesday, March 2

  • Algol should be at minimum light for a couple hours centered on 8:20 p.m. EST.

    Wednesday, March 3

  • This is the time of year when bright Sirius stands at its highest due south right after dark. If you've got an 8-inch or larger scope, have you ever tried for the faint companion of Sirius? It's a tricky challenge and requires a night of excellent, steady seeing (being 10,000 times fainter than Sirius A), but it's now a good 9.1 arcseconds due east of the bright primary — wider than it's been for nearly three decades. For more information see the March Sky & Telescope, page 47, and especially the February 2008 issue, page 33.

    Thursday, March 4

  • Sometime around 8:00 p.m. (depending on where you live east or west in your time zone) the Big Dipper will have risen as high in the northeast as Cassiopeia has sunk in the northwest. Spring is on the way!

    Friday, March 5

  • Before dawn Saturday morning, look south for the last-quarter Moon — with Antares to its left and the stars of Scorpius's head around it.

    Saturday, March 6

  • Leo is a land of double stars. Tour them using Richard Jaworski's "Seeing Double" article and chart in the March Sky & Telescope, page 73.

    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

    Mars on March 3, 2010

    Mars is gibbous now; it's more than a month past opposition. The north polar cap (bottom) remains big and bright despite the advance of spring in the Martian northern hemisphere. At center-left is dark Syrtis Major; at upper right are dark Sinus Sabaeus and Sinus Meridiani. At top, the Hellas region is slightly bright.

    Christopher Go in the Philippines took this image at 14:00 UT March 3rd, when the central meridian longitude was 321°. Stacked-video imagery like this can show detail on a planet much more clearly than the eye can see through the same telescope.

    Christopher Go


    Mercury is hidden behind the glare of the Sun.

    Venus (magnitude –3.9) is slowly emerging into view very low in the sunset. Look for it just above the western horizon about 30 minutes after sundown. Binoculars help. Venus will gradually creep up into better twilight visibility for the next threre months.

    Mars, still bright at magnitude –0.6, shines high in the east at dusk and highest in the south around 9 or 10 p.m. It's located in Cancer, below Pollux and Castor after dusk.

    In a telescope Mars is shrinking: from 12.4 to 11.6 arcseconds wide this week. Its north polar cap remains the most visible marking. Identify other surface features you detect in your scope using the Mars map and observing guide in the December issue of Sky & Telescope, page 57.

    Jupiter is out of sight in conjunction with the Sun.

    Saturn on Feb. 27, 2010

    "Here's my first image of Saturn this season," writes Christopher Go from the Philippines. "The South Equatorial Belt [above center] is very dark. The color of both hemispheres are almost the same but the north is slightly darker. Lots of belt details on both hemispheres. The North Polar Region is dark." South is up; we'll be looking at the north face of the rings for the next 15 years.

    Go images the planets with a Celestron 11 scope on an AP900GTO mount using a DMK 21F04 camera. Stacked-video images like this show more detail than the eye can see even through the same telescope.

    Christopher Go


    Saturn (magnitude +0.6, in western Virgo) rises in the east around the end of twilight and stands highest in the south around 1 a.m. In a telescope, Saturn's rings are tilted only 4° from edge-on to us, as seen at right. They'll narrow further (to 1.7°) in the coming months.

    Uranus and Neptune are behind the glare of the Sun.

    Pluto is up 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.

    To be sure to get the current Sky at a Glance, bookmark this URL:
    http://SkyandTelescope.com/observing/ataglance?1=1

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    • About Alan MacRobert

    Alan M. MacRobert became an avid Sky & Telescope subscriber in 1966 at age 14, joined the editorial staff in 1982, and is now a senior contributing editor, semi-retired. He played a role in practically every part of the magazine and the company's other products for more than a generation, both on the amateur-observing side and the science-reporting side. In 1994 a book collection of his observing how-tos and telescopic sky tours was published as Star Hopping for Backyard Astronomers. He has produced This Week's Sky at a Glance online every week since 1989.

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