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University of Minnesota

Minnesota Starwatch

University of Minnesota

Minnesota Institute for Astrophysics

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Starwatch Newsletter

Minnesota Starwatch is a newsletter describing the night sky in the Midwest. Updated monthly, it is produced by the

Minnesota Institute for Astrophysics
University of Minnesota
100 Pleasant Street SE, Minneapolis, MN 55455

Minnesota Starwatch for March 2017

by Deane Morrison

The five planets that adorned the morning sky last month are now going their separate ways. Mercury slips behind the sun on March 23, and Venus glides into the sun/s foreglow as it heads for a similar trip in early June.

As for Jupiter, Earth passes it on March 8, when it is said to be at opposition because it appears opposite the sun in the sky. On that day the giant planet rises around sunset and sets around sunrise. This is a great time to observe it, even if all you have is binoculars. As the days go by, Jupiter rises earlier each evening and moves westward as Earth leaves it behind in the orbital race.

But Mars and Saturn remain strictly morning planets. They are up in the south an hour before sunrise, and during March they cut the gap between them by half. The planets bracket the bright red star Antares, in Scorpius, whose name means "rival of Mars." This is a fine opportunity to compare Mars, the westernmost of the three bodies, with its rival, especially with Mars brightening as it heads toward opposition later this year.

The spring equinox happens at 11:30 p.m. March 19, when the sun crosses the equator into the northern sky and the Earth is lighted from pole to pole.

March's moon reaches fullness at 7:01 a.m. on the 23rd. This could be close to the time of moonset in your area, so you may want to get outside by 6:30 to be sure of seeing it hanging over the western horizon.

On moonless evenings in the last week of March, look for the zodiacal light in the west as evening twilight fades. This elusive, faint cone of light appears in the evening sky in late winter/early spring; in fall, it appears in the morning sky. It extends from the horizon along the sun's path and is caused by sunlight reflecting off dust in the plane of the solar system.

In astronomy news, scientists—including physicists from the University of Minnesota—have just achieved the first detection of gravitational waves. Gravitational waves are produced by violent, cataclysmic events like mergers between black holes or the explosions of stars known as supernovas, events that shake the very fabric of space. The waves are actually ripples in space, radiating out from their point of origin.

The gravitational waves that were detected came from the merger of two black holes to form a bigger black hole with a mass 62 times that of the sun. It happened about 1.3 billion years ago, and the signal from it just reached Earth last September. Einstein's theory of general relativity predicted these waves 100 years ago, and now that the scientists know they can detect them, they can look for more of them and figure out from the exact form of the waves what sorts of events caused them. That means a much more complete picture of what has been going on in the Universe around us.

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:

02/26/17 Contact: Deane Morrison, University Relations, (612) 624-2346,

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