Starwatch: March skies filled to the brim

Published 10:58 am Saturday, February 24, 2018

By Deane Morrison

University of Minnesota

With two full moons and the spring equinox, what’s not to love about March?

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The first full moon arrives at 6:51 p.m. on the 1st, barely an hour after moonrise and just a couple of days after perigee, its closest approach to Earth in a lunar cycle. This means it’ll rise about as round and luminous as any full moon gets.

Looking up to March. Photo provided

The second arrives at 7:37 a.m. on the 31st. As the second full moon in a calendar month, it qualifies as a blue moon. However, it sets that morning shortly before the instant of fullness, so you may want to check your local time of moonset before deciding whether to get up to see it or to enjoy it the evening of the 30th.

Venus and Mercury appear very low in the west after sunset, bathed in the sun’s afterglow. The planets are closest on the 3rd, but easy to tell apart because Venus outshines Mercury. After the 15th, Mercury plummets toward the horizon and is soon lost.

In the predawn sky, look south to see brilliant Jupiter. East of Jupiter, Mars is brightening as it moves swiftly eastward. Its motion carries it away from Jupiter and Scorpius, with its red heart, Antares (the “rival of Mars”), and toward Saturn, a shiny dot above the Teapot of Sagittarius. Mars waxes brighter every morning because Earth is gaining on it in the orbital race. This summer, we’ll lap the red planet and it will be a treat for the eye.

On evenings between the 3rd and 18th, look for the elusive zodiacal light, a faint glow extending up from the western horizon along the sun’s path shortly after nightfall. It comes from sunlight reflecting off dust in the plane of the solar system.

Spring arrives with the vernal equinox at 11:15 a.m. on the 20th. At that moment, the sun crosses the equator into the northern sky and Earth will be lighted from pole to pole.

With the sun’s crossing comes a turning point in day length. During fall and winter, travelers in the Northern Hemisphere who are heading north see the day length shorten. But after the March equinox, going farther north means a longer day length. Also, the day length increases fastest around the time of the spring equinox because this is when the sun is moving most rapidly north.

The University of Minnesota offers public viewings of the night sky at its Duluth and Twin Cities campuses. For more information and viewing schedules, see:
Duluth, Marshall W. Alworth Planetarium:
Twin Cities, Minnesota Institute for Astrophysics (during fall and spring semesters):
Check out the astronomy programs at the University of Minnesota’s Bell Museum ExploraDome:

Contact: Deane Morrison, University Relations, (612) 624-2346,

Find U of M astronomers and links to the world of astronomy at