This Week’s Sky at a Glance, March 25 – April 2

Friday, March 25

All this week Jupiter, with Leo over it, continues to highlight the eastern sky after dusk.

The waning Moon groups up with Mars, Saturn, and Antares on Monday and Tuesday mornings, March 28th and 29th.

• By 11 p.m. now, the bowl of the Big Dipper stands upside down high in the north-northeast, straight over the bowl of the dim Little Dipper as if dumping water into it. In the fall, they do the reverse.

Saturday, March 26

• The huge, bright Winter Hexagon is still in view after dark, filling the sky to the southwest and west. It's the biggest well-known asterism in the sky. Start with brilliant Sirius in the southwest, the Hexagon's lower left corner. High above Sirius is Procyon. From there look even higher for Pollux and Castor, rightward from Castor to Menkalinan and bright Capella, lower left from there to Aldebaran, lower left to Rigel at the bottom of Orion, and back to Sirius.

Sunday, March 27

• Draw a line from Castor through Pollux, and follow it farther out by a big 26° (about 2½ fist-widths at arm's length). You're at the dim head of Hydra, the Sea Serpent. In a dark sky it's a subtle but distinctive asterism about the size of your thumb at arm's length. Binoculars show it easily through light pollution.

Monday, March 28

• Look south before dawn tomorrow morning the 29th for the waning Moon, Saturn, Mars, and Antares forming an uneven quadrangle, as shown at right.

Tuesday, March 29

• Jupiter's Great Red Spot should cross Jupiter's central meridian around 10:11 p.m. Eastern Daylight Time. At 10:54 p.m. EDT, Io disappears behind Jupiter's celestial-western limb. Io reappears from eclipse out of Jupiter's shadow at 1:41 a.m. EDT, just off Jupiter's opposite limb. Subtract three hours from these times to get PDT.

Wednesday, March 30

• Last-quarter Moon tonight (exact at 11:17 a.m. Thursday EDT). The Moon rises very late, around 2 a.m. local time, with Mars and Saturn pointing down to it from the upper right.

Thursday, March 31

• With the Moon out of the evening sky, try exploring the galaxy groups around Gamma Leonis (Algieba) in the Sickle of Leo, using Sue French's Deep-Sky Wonders article, charts, and photos in the April Sky & Telescope, page 54. Did you know there was so much here? You'll need a dark sky.

The Gemini twins overlook Procyon very high in the southwest after dark this week. The three labeled stars here are part of the enormous Winter Hexagon. The star cluster left of Pollux near the edge is M44, the Beehive in Cancer.
Akira Fujii

Friday, April 1

• Arcturus shines brightly in the east these evenings. The Big Dipper, high in the northeast, points its curving handle lower right down toward it. Arcturus forms the pointy end of a long, narrow kite asterism formed by the brightest stars of Bootes, the Cowherd. The kite is currently lying on its side to Arcturus's left. The head of the kite, at the far left, is bent slightly upward. The kite is 23° long, about two fist-widths at arm's length.

• This evening, telescope users along a narrow path from the Seattle/Vancouver area to Arkansas can watch for a 9.5-magnitude star (located 10° northwest of the Pleiades) to disappear for up to 9 seconds behind the invisibly faint asteroid 2892 Filipenko. Track map and finder charts for the shadow path across the US, the star to be occulted, and the times.

Saturday, April 2

• This is the time of year when, at the end of twilight, Arcturus, the bright Spring Star, shines just as high in the east as Sirius, the brighter Winter Star, does in the southwest (for viewers at mid-northern latitudes).
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Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

This is an outdoor nature hobby. 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 guide to astronomy.

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but it's less than one per square degree on the sky. Also plotted are many hundreds of telescopic galaxies, star clusters, and nebulae. Shown above is the new Jumbo Edition for easier reading in the night. Click image for larger view.

Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or new Jumbo Edition), which shows stars to magnitude 7.6.

Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5, nearly three times as many. The next up, once you know your way around, is the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger Night Sky Observer's Guide by Kepple and Sanner.

Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (meaning heavy and expensive). 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."

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This Week's Planet Roundup

Mars on March 23rd, imaged by Christopher Gowith a 14-inch scope. South is up. The big white patch at top is not the South Polar Cap or South Polar Cloud Hood but the Hellas basin, which often fills with clouds or frost. The now-small North Polar cap is at bottom. The big dark peninsula at center is Syrtis Major; Hellas is due south of this landmark. Extending to the right-hand limb (celestial east; following ) is thinner Sinus Sabaeus ending with Sinus Meridiani. The dark arc just inside the entire bright limb is a processing artifact. Watch out for these "echoing" bright/dark borders in planetary images.

Jupiter's Great Red Spot is still strikingly red. Christopher Go took this image at 16:45 March 5th UT, just a few minutes before the spot reached the central meridian. South is up. Notice the smooth vs. turbulent difference in the South Equatorial Belt preceding (left) and following the Red Spot.

Mercury is buried deep in the glow of sunset.

Venus is deep in the glow of sunrise.

Mars (about magnitude –0.5, at the head of Scorpius), rises around midnight daylight-saving time. Before dawn it blazes yellow-orange in the south, to the right of dimmer Saturn. In a telescope Mars is about 12 arcseconds in diameter — quite big enough now to show surface features in a good 3-inch scope at high power during good seeing.

By its opposition and closest approach in late May, Mars will quadruple in brightness and grow to 18.6 arcseconds wide. See our telescopic guide to Mars in the April Sky & Telescope, page 48.

Jupiter (magnitude –2.4, near the hind foot of Leo) shines high in the southeast after dusk and highest in the south by 11 or midnight. It sets in the west before sunrise. See our telescopic guide to Jupiter in the March Sky & Telescope, page 48.

Saturn (magnitude +0.4, in the legs of Ophiuchus) rises around midnight or a bit later, 10° lower left of Mars. By early dawn they stand in the south — Saturn on the left, bright Mars on the right — with fainter, Mars-colored Antares below them making it a triangle.

Uranus and Neptune are hidden in the glare of the Sun.

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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) is Universal Time (UT, UTC, or GMT) minus 5 hours.

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“This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours.”

— Neil deGrasse Tyson