For instance, in Boston this evening the Belt should be perfectly horizontal around 8:20 p.m. How accurately can you time this event at your location? Orion's Belt is slightly curved, so judge by the two stars on its ends. Can you find a sighting reference to make your measurement more precise, and track the time's day-to-day change? Welcome to pre-telescopic astronomy.

Saturday, March 20

For the U.S. and Canada, writes David Dunham of the International Occultation Timing Association, "Several 8th to 6th magnitude stars will be occulted, and one 5th-mag. star. Predictions of these (and of other total lunar occultations for all of 2010 for stars to mag. 6.0) for 40 of the larger North American cities can be downloaded in .zip files from Bob Sandy's website. There are some regional sites with predictions of fainter stars, for example for stars to 8th mag. in the Mid-Atlantic region (computed for near Washington, DC) at the bottom of my Mid-Atlantic occultation and expedition page."

Sunday, March 21

Monday, March 22

Wednesday, March 24

Thursday, March 25

Friday, March 26

Saturday, March 27

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.

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.

Sky & 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).

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."

Mars was only 10.8 arcseconds wide on the evening of March 16th when S&T's Sean Walker took this image at 7:41 p.m. EDT. The North Polar Cap (bottom) seems to be diminishing. Note the cloud in Hellas (at the 11 o'clock position on the limb) and the apparent blue cloud over Syrtis Major (left limb). Walker used a DMK camera on a Celestron 14-inch Schmidt-Cassegrain scope. He writes, "One hour later, the seeing was so bad I couldn’t be sure there was a polar cap on Mars!"

S&T: Sean Walker

Venus (magnitude –3.9) is slowly emerging into better view low in the evening twilight. Look for it almost due west as sunset fades.

Mars, now dimming into the distance at magnitude –0.1, shines very high in the southeast to south in early evening, and southwest later. It's in Cancer, drawing away from Pollux and Castor in Gemini.

In a telescope Mars is gibbous and shrinking: from 10.3 to 9.7 arcseconds in diameter this week. The north polar cap remains its most visible marking. Identify other surface features using the Mars map and observing guide in the December Sky & Telescope, page 57.

Jupiter is still hidden in the glow of sunrise.

The giant, long-lived thunderstorm on Saturn known as the Saturn Electrostatic Disturbance (SED), a source of radio emissions detected by the Cassini spacecraft, has returned to amateur visibility as a small white spot, at least for users of large scopes and/or during moments of excellent seeing. It's above center barely past the central meridian here. "The SED is really brightening now!" writes Christopher Go, who took this image. "It is much more prominent than when I last imaged it." Update: As of March 18th it was fading and had reportedly split in two.

Go took this image at 16:48 UT March 13, 2010. The spot is near System III longitude 0°, System II longitude 236°. In addition, he notes, "The [dark] South Equatorial Belt is very prominent, while the North Equatorial Belt looks faint. There are a lot of band details, especially in the northern hemisphere."

Little Dione is in the background below the right end of the rings. South is up. Click image for a .wmv movie of eight images (with north up).

Christopher Go

Uranus and Neptune are hidden in the glow of sunrise.

Pluto (magnitude 14, in northwestern Sagittarius) is well up in the south-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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