Sky at a Glance | March 21st, 2014

By: Alan MacRobert March 21, 2014 0

Jupiter, among the legs of Gemini all week, forms the top of this year's Winter Diamond — which is still standing high as spring pushes winter aside. Procyon and Betelgeuse form the Diamond's side corners. This is how they're oriented in twilight as the stars come out. (Sirius is the Diamond's bottom.)

The 3rd-magnitude star closest to Jupiter is Epsilon Geminorum, a yellow-orange supergiant 900 light-years away. Can you see its tint with your unaided eyes?

Sky & Telescope

Friday, March 21

This year's huge "Winter Diamond" — bright Jupiter on top, bright Sirius on the bottom, and Procyon and Betelgeuse forming the left and right corners — persists well into spring. It stands straight up in the south around 7 p.m. now (depending on where you live east or west in your time zone), then tips westward as the evening advances.

Saturday, March 22

When the stars come out this week, the Big Dipper is standing on its handle in the northeast. As evening grows late, the Dipper climbs higher and starts tipping to the left.

Sunday, March 23

Double shadow transit on Jupiter: Ganymede and Io are both casting their tiny black shadows onto the giant planet from 10:08 to 10:32 p.m. EDT (9:08 to 9:32 p.m. CDT).

Last quarter Moon (exact at 9:46 p.m. EDT). The Moon, in northern Sagittarius, rises around 2 or 3 a.m. Monday morning. By dawn Monday look for Antares very far to the Moon's right, Altair about equally far to the Moon's upper left, and bright Venus about equally far to its lower left.

Monday, March 24

By 10 or 11 p.m. Mars and Spica are well up in the southeast. Look almost two fists at arm's length to their right for the four-star pattern of Corvus, the Crow. Normally the Crow eyes Spica in Virgo's hand. Now he may be more interested in the brighter shiny right close by.

Tuesday, March 25

The biggest and brightest asteroids, 1 Ceres and 4 Vesta respectively, are only about 2° apart in eastern Virgo in the early morning hours, some 12° northeast of Mars. They've brightened to magnitudes 7.3 and 6.1, respectively. They'll be at opposition in mid-April. Use our finder chart for Ceres and Vesta.

The waning Moon pairs with Venus on Thursday morning the 27th in the longitudes of the Americas. 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. The Moon here is drawn three times actual size.

Sky & Telescope

Wednesday, March 26

As dawn brightens on Thursday morning the 27th, you'll find Venus near the thin waning crescent Moon, as shown here.

Thursday, March 27

On the traditional divide between the winter and spring sky is the dim constellation Cancer. It's between Gemini to its west and Leo to its east. Cancer holds a unique object: the Beehive Star Cluster, M44, in its middle. The Beehive shows to the naked eye as a dim, cloudy glow if your sky is fairly dark. Look for it a little less than halfway from Pollux to Regulus. With binoculars it's a snap even in a polluted sky.

Friday, March 28

The huge, bright Winter Hexagon nearly fills the southwestern sky at dusk. Start with bright Sirius in the south, marking the Hexagon's lower left corner. High above Sirius is Procyon. From there look even higher to Pollux and Castor with bright Jupiter below them, then from Castor farther lower right to Menkalinen and Capella, then lower left to Aldebaran, then duck lower left around to Rigel at the bottom of Orion, and back to Sirius. Within the Hexagon shine Jupiter and Betelgeuse.

Saturday, March 29

You can tell winter is gone for good, astronomically speaking: As soon as the stars come out, the Big Dipper is already higher in the northeast than Cassiopeia is in the northwest.

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. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

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 the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and once you know your way around, 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, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.

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 (able to point with better than 0.2° repeatability, which means fairly heavy and expensive). As Terence Dickinson and Alan Dyer say in their invaluable 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

Unlike Jupiter's moons Io and Europa, Ganymede and Callisto are darker than most of Jupiter's surface, as seen dramatically in this high-resolution image of Ganymede near Jupiter's central meridian taken by Christopher Go at 11:20 UT March 2nd. You might even mistake it for its shadow! (The faint light ring that appears inside Ganymede is a processing artifact caused by its sharp dark edge against the lighter background).

South is up. The reddish oval near Ganymede is Oval BA in the South Temperate Zone.

Christopher Go

Mercury (magnitude 0.0) is very low above the east-southeast horizon a half hour before sunrise. It's moving a little lower each day. Look for it about 20° lower left of bright Venus. Binoculars will help.

Venus (magnitude –4.5) rises as the bright "Morning Star" just before the beginning of dawn and moves higher as the sky lightens; look southeast. In a telescope it appears just about half lit.

Mars (magnitude –1.1, in Virgo) rises around nightfall — a fiery blaze with fainter Spica 5° to its lower right. They're highest in the south around 2 or 3 a.m. daylight-saving time, with Spica now under Mars.

In a telescope Mars has grown to 14 arcseconds wide, almost as large as the 15.1″ it will attain when passing closest by Earth in mid-April. See the telescopic Mars map and observing guide in the March Sky & Telescope, page 50.

Jupiter, magnitude –2.3, in Gemini, dominates the sky overhead in twilight (for midnorthern skywatchers). It sinks westward through the evening and sets around 3 a.m. See our articles on observing Jupiter in the January Sky & Telescope or the briefer online introduction Jupiter: Big, Bright, and Beautiful.

Saturn (magnitude +0.3, in Libra) rises around 11 p.m. and is highest in the south around 4 a.m. By then it's far left of Mars and Spica, and less far to the upper right of Antares. Saturn's rings are tilted a wide 22° to our line of sight for most of this spring.

Uranus and Neptune are lost behind the glare of the Sun.

"We may be little guys, but we don’t think small. It’s the courage of questions, of grasping our true circumstances, and not pretending we are at the center of it all, that is adulthood."
— Ann Druyan, 2014

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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.