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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 August 2016

by Deane Morrison

As August begins, Jupiter comes out in the sun's afterglow and soon drops out of sight. High in the southwest, the brilliant star Arcturus starts a month-long plummet to the horizon, dragging its kite-shaped constellation, Bootes the herdsman, along with it. And low in the southwest, Mars provides its own spectacle as it journeys eastward for a rendezvous with Saturn and the bright red star Antares, the "rival of Mars."

Watch Mars as it first sails through the crown of Scorpius, a nearly vertical line of three stars west of Antares, the heart of the scorpion. Then, in the third week of August, Mars moves in on Antares. Between the 21st and 25th, don't miss the close en-counter between Mars and its stellar rival as the red planet glides between Antares and Saturn, the bright light above the star. Mars keeps going east and ends the month forming the eastern point of a triangle with Antares and Saturn.

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Look just east of Scorpius for the Teapot of Sagittarius, whose spout tips down to-ward the scorpion's tail. Above the handle of the Teapot hangs the little Teaspoon of stars.

High in the east, the Summer Triangle of bright stars dominates. Forming its points are Altair, in Aquila the eagle, the southernmost; Deneb, in Cygnus the swan, to the northeast; and Vega, the powerhouse star in Lyra the lyre, to the northwest. Use a star chart to find these constellations and also the Northern Cross, a prominent feature of Cygnus.

The annual Perseid meteor shower is predicted to peak on the morning of the 12th. Meteors should begin flying in late evening on the 11th, and after 1 a.m. on the 12th no moon will interfere. Perseids radiate from the northeast and often leave persistent trails. The shower gradually intensifies from the first days of August through the peak, then drops off rapidly. With no moon and dark skies, we could see one or two meteors per minute, with the highest frequency occurring in the predawn hours.

When we see the Perseid meteors, we're seeing grains of comet dust and pebbles burning up in the atmosphere. Meteor showers happen when Earth plows through one of the many clouds of dust given off by various comets as they passed through our vicinity.

These meteors also strike the moon, and since it has no atmosphere to burn them up, they hit the surface and sometimes cause flashes of light visible through small telescopes. They leave small craters, too. After all, they move at some 35 miles per second. The parent comet of the Perseids is known as Swift-Tuttle, after the two astronomers who discovered it. It comes around every 133 years, and it last visited in 1992.

August's full "green corn moon" arrives at 4:26 a.m. on the 18th. That's well before moonset, at which point it'll still be quite round and beautiful.

Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet

Twin Cities, Minnesota Institute for Astrophysics (during fall and spring semesters): www.astro.umn.edu/outreach/pubnight

Check out the astronomy programs at the University of Minnesota's Bell Museum ExploraDome: www.bellmuseum.umn.edu/ForGroups/ExploraDome/index.htm

07/21/16 Contact: Deane Morrison, University Relations, (612) 624-2346,

Find U of M astronomers and links to the world of astronomy at http://www.astro.umn.edu.