By Deane Morrison

A University of Minnesota feature

August is a great month for vacations, and even the planets seem to be at play.

Take Mars, for example. Last month its eastward motion carried it past its longtime companion, the bright star Spica, in Virgo. As August begins, Mars is in the southwest, almost midway between Spica to the west and Saturn to the east. Continuing its eastward trek, the Red Planet glides below Saturn, coming closest on the 25. On the 31, the two planets form a triangle with a fat crescent moon.

The moon, too, is at play. It becomes full at 1:09 p.m. on the 10th, less than an hour before reaching perigee, the closest point to Earth in its orbit. This is the closest perigee of the year, so the moon will be big and beautiful; however, it won’t rise over our area of the planet until at least 8 p.m. that night—after waning for seven hours.

On the night of the 12th-13th, the moon will be past full but plenty bright enough to wash out many of the Perseid meteors at the shower’s peak. Perseids are often bright themselves, though, so look to the northeast in the late evening or predawn hours and hope for the best.

A note about full moons past and future. July’s full moon was hailed as a “supermoon” because it fell within a day of perigee. In the Twin Cities, the best time to see that moon full and still above the horizon was around 5:45 a.m. on July 12, some 21.5 hours before perigee. In September, the interval between perigee and the best time to see it close to full will be nearly the same, but this time fullness occurs in early evening, not first thing in the morning.

So if you missed the show in July, September’s should rival it and happen at a more convenient hour for us in the Midwest. (August’s full moon is also super—astronomers use the term perigee moon rather than supermoon—especially on the other side of the Atlantic, where it rises much closer to full.)

Ornamenting it high in the southeast is the Summer Triangle of the bright stars Vega, Deneb, and Altair. Deneb, at the Triangle’s northeast corner, is both the tail of Cygnus, the swan, and the top of the Northern Cross. At the northwest corner, brilliant Vega presides over the parallelogram-shaped Lyra, the lyre of Orpheus. At the southern point is Altair, the brightest star in Aquila, the eagle.

Above Altair, use a star chart to find needle-thin Sagitta, the arrow that, according to one myth, Hercules used to kill the mythical Aquila. And just above and right (west) of Sagitta, use binoculars to find the almost upside-down Coathanger of stars, not quite halfway from Altair to Vega.

If you’re up in the predawn hour (or two), look for the faint zodiacal light in the east, along the sun’s path. This lovely glow comes from sunlight reflecting off dust in the plane of the solar system.

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: 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.

Contact: Deane Morrison, University Relations, 612-624-2346,morri029@umn.edu.

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