Every year March ushers in spring, whose inexorable advance sends the nighttime hours into a grand retreat. But those hours still leave plenty of time to watch the parade of stars and planets. This month Mars, having riveted the attention of backyard astronomers for several weeks, yields the spotlight to Saturn.
Both planets are well up in the south after nightfall, flanking the kingly form of Leo, the lion. Mars shines west of the Sickle of stars outlining Leo's head, while Saturn, in Virgo, appears just below and slightly east of the hindquarters. Midway between the planets, the bright star Regulus marks the heart of the lion.
Earth has already left Mars behind in the race around the sun, and on the night of the 21st it will do the same to Saturn. At that moment, we'll pass a cozy 790 million miles from the ringed planet, which will be up all night. Though Saturn will be quite bright, its usually glorious gossamer girdle won't contribute much to its sheen.
Already close to edgewise, the rings are narrowing, taking with them some of the planet's luster.
In the west, Venus, fresh from a trip behind the sun, slowly makes its way up out of the sunset afterglow. Mercury pops in for a visit in the last few days of the month, appearing as a dimmer light to the lower right of Venus.
ADVERTISEMENT
Venus, Mars and Saturn will remain in the evening sky until the end of summer. Watch them draw ever closer, ending in a tight grouping above the western horizon in August.
March is a good month to try to spot the Three Leaps of the Gazelle, three pairs of somewhat dim stars forming a southeast-to-northwest line just north of Leo. Look between Leo and the Big Dipper to find two star pairs, then about the same distance to the northwest for the third.
An especially lovely full moon rises at sunset on the 29th, less than two hours before the moment of complete fullness. This moon was known to Algonquin Indians by many names, such as the crow moon, for the cawing of crows this time of year; the crust moon, for the crust on the snow formed by thawing and refreezing; and the sap moon, for the running of maple sap.
March's biggest event, though, is the coming of spring. It arrives officially with the vernal equinox at 12:32 p.m. on the 20th, when the sun sails over the equator into the northern sky.
The coming of spring is, of course, a gradual process, but the sun's northward motion is fastest this month, and so this is when we most notice the lengthening of days. In the Twin Cities, we gain an hour and 34 minutes of daylight during March. That change may seem rapid, but it pales in comparison to the pace in Anchorage, Alaska. There the gain is two hours and 53 minutes.
Daylight Saving time returns at 2 a.m. on the 14th. Clocks move forward one hour.
The University of Minnesota offers public viewings of the night sky at its Morris, Duluth and Twin Cities campuses. For more information and viewing schedules in Duluth, go to Marshall W. Alworth Planetarium, www.d.umn.edu/~planet .
