The Night Sky of March

Dr. Wayne Wooten
Professor of Astronomy

For March 2011, the Moon will be a waning crescent as the month begins; it will be 1.6 degrees NW of Venus in the dawn on the 1st, and new moon on March 4th. The waxing crescent moon passes five degrees north of Jupiter in SW twilight on March 6th. First quarter moon sits high in the sky and half-lit at sunset on March 12th. We spring forward to Daylight Savings Time on Sunday, March 13th. Full Moon, the Grass Moon, falls on March 19th. The Vernal Equinox occurs at 6:21 PM on March 20th. Because Easter Sunday is the Sunday following the Full Moon that follows the Vernal Equinox, this means Easter Sunday will fall late in April this year. The last quarter moon is high overhead at sunrise on March 26th.

Jupiter binds us adieu in March, passing into the sun’s glare by month’s end. But on March 15th, Mercury and Jupiter appear two degrees apart in western twilight, about 45 minutes after sunset. This is your best chance to see the elusive inner planet this year in the evening sky. It climbs higher in the sky, leaving Jupiter behind, to reach greatest eastern elongation on March 23rd, about 18 degrees from the Sun, and setting about an hour after sunset.

In March, NASA’s Messenger orbiter enters orbit and should begin an intensive study of Mercury, so by the end of this month, we will probably have our first global view of Mercury. By month’s end, it retrogrades between us and the sun, and joins Jupiter in Sun’s glare. Venus too is heading sunward, moving eastward in the morning sky to vanish in sun’s glare in April for several months. Mars also now is near superior conjunction, behind the Sun. So who is left?

On April 3rd, we pass between Saturn and the Sun, so Saturn will rise in the east in Virgo, above the bright star Spica, thus staying up all night. As we are then closest to the ringed wonder, this is the best time to observe the most beautiful object in the sky. When viewed with a telescope, the rings will be even open than last year, tilted about 11 degrees toward the Earth and Sun this year. Small scopes will also show its largest moon Titan. In early April, Saturn will be the only naked eye planet in the sky for several weeks.

The constellation Cassiopeia makes a striking W in the NW. South of Cassiopeia is Andromeda’s hero, Perseus. Between him and Cassiopeia is the fine Double Cluster, faintly visible with the naked eye and two fine binocular objects in the same field. Perseus contains the famed eclipsing binary star Algol, where the Arabs imagined the eye of the gorgon Medusa would lie. It fades to a third its normal brightness for six out of every 70 hours, as a larger but cooler orange giant covers about 80% of the smaller but hotter and thus brighter companion as seen from Earth.

At Perseus’ feet for the famed Pleiades cluster; they lie about 400 light years distant, and over 250 stars are members of this fine group. East of the seven sisters is the V of stars marking the face of Taurus the Bull, with bright orange Aldebaran as his eye. The V of stars is the Hyades cluster, older than the blue Pleiades, but about half their distance. Yellow Capella, a giant star the same temperature and color as our much smaller Sun, dominates the overhead sky in the northwest. It is part of the pentagon on stars making up Auriga, the Charioteer (think Ben Hur). Several nice binocular Messier open clusters are found in the winter milky way here. East of Auriga, the twins, Castor and Pollux highlight the Gemini; it is directly above us as darkness falls in early March. UWF alumni can associate the pair with Jason and the Golden Fleece legend, for they were the first two Argonauts to sign up on his crew of adventurers.

South of Gemini, Orion is the most familiar winter constellation, dominating the southern sky at dusk. The reddish supergiant Betelguese marks his eastern shoulder, while blue-white supergiant Rigel stands opposite on his west knee. Just south of the belt, hanging like a sword downward, is M-42, the Great Nebula of Orion, an outstanding binocular and telescopic stellar nursery. The bright diamond of four stars that light it up are the trapezium cluster, one of the finest sights in a telescope.

In the east are the hunter’s two faithful companions, Canis major and minor. Procyon is the bright star in the little dog, and rises minutes before Sirius, the brightest star in the sky. Sirius dominates the SE sky as darkness falls. At 8 light years distance, Sirius is the closest star we can easily see with the naked eye from West Florida.

When Sirius is highest, along our southern horizon look for the second brightest star, Canopus, getting just above the horizon and sparkling like an exquisite diamond as the turbulent winter air twists and turns this shaft of starlight, after a trip of about 200 years!

To the northeast, look for the bowl of the Big Dipper rising, with the top two stars, the pointers, giving you a line to find Polaris, the Pole Star. Look for Mizar-Alcor, a nice naked eye double star, in the bend of the big dipper’s handle, rising by 7 PM at the start of March. Above the bowl, in the head of Ursa major, are the colliding galaxies M-81 and M-82, our photo feature for this month.

March comes in like a Lion, as Leo rises just at sunset. If you take the pointers of the Big Dipper’s bowl to the south, you are guided instead to the head of Leo the Lion rising in the east, looking much like the profile of the famed Sphinx. The bright star at the Lion’s heart is Regulus, the "regal star".

If you follow the handle of the Big Dipper to the south, by 9 PM you will be able to "arc to Arcturus", the brightest star of Spring and distinctly orange in color. It color is an indication of its uniqueness. It large speed and direction through the Milky Way suggests it was not formed with our Galaxy, but is a recent capture from the Sagittarius Dwarf Galaxy, a smaller satellite galaxy now being assimilated by our huge spiral galaxy. Many of its lost stars, like Arcturus, follow a band across the sky at about a 70 degree angle to our galactic plane. Arcturus is at the tail of kite shaped Bootes, the celestrial bear driver chasing the two bears from his flocks.

By 9 PM, many more galaxies will be following as the Virgo Supercluster, just above Saturn now, rises in the east. This huge cluster of over a thousand galaxies is centered about 60 million light years away. The brightest star of Virgo, Spica, lies just east of the center of the cluster, and its rise just after sunset marks the time of year for spring planting in folklore. Time to get your peas in the ground….

March goes out like a lamb, not just from Easter tradition, but because Aries the Ram is setting in the west by the end of March. Many of our sayings and traditions have astronomical origins.

Read past issues of the Sky at Night