University of Minnesota
September 16, 2010
Just as the mythological winged horse Pegasus flew over the Mediterranean, so its starry namesake sails above a sea of watery fall constellations.
Pegasus puts its unmistakable stamp on the sky with the Great Square, now high in the south after nightfall. Right below the Great Square is a subdued but pretty ring of stars called the Circlet of Pisces, the fish.
Just southwest of the Circlet you’ll find the Y-shaped Water Jar, the apex of the spidery-shaped constellation Aquarius, the water bearer. Moving southwest again, a chevron of stars outlines Capricornus, the sea goat.
The lone bright star in the neighborhood is Fomalhaut, a lantern low in the south. This intriguing star, beloved of science fiction writers, marks the mouth of Piscis Austrinus, the southern fish.
Only 25 light-years from Earth, Fomalhaut delighted astronomers five years ago when they discovered a gigantic ring of dust circling the star. The ring is made of debris from collisions of countless small objects in orbit around the star, yet the ring is not centered on the star. It owes its off-center position to the gravitational influence of a large planet, found in 2008, orbiting Fomalhaut at a distance of about 10 billion miles; that’s 115 times the distance between Earth and the sun.
Speaking of planets, the water constellations host a prominent guest this year. Jupiter, a gorgeous beacon, lights up the sky below the Circlet of Pisces. The king of planets is almost as bright as it can get and remains visible most of the night.
Morning star watchers will see Saturn rising earlier every day. The ringed planet ends October by popping into the eastern sky a good two and a half hours before the sun.
October’s full moon, known to Algonquin Indians as the hunter’s moon, rises round and beautiful the evening of the 22nd. The month closes out with Halloween, an ancient Celtic holiday known as Samhain.
One of four cross-quarter days falling midway between an equinox and a solstice, Samhain began at sundown and ushered in the dark half of the year. On that night, evil spirits cooped up for six months came bursting out of confinement to wreak havoc on mankind and had to be placated with bribes of food. Thus began our tradition of trick-or-treating. The unfriendly spirits hung around until May Day, when the light half of the year began and they were once again banished from the world of the living.
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 see:
Morris, UMN 16-inch telescope schedule: cda.mrs.umn.edu/~kearnsk/Telescope/PubObs.htm
Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet
Twin Cities, Department of Astronomy (during fall and spring semesters): www.astro.umn.edu/outreach/pubnight
Find U of M astronomers and links to the world of astronomy at http://www.astro.umn.edu
Contact: Deane Morrison, University Relations, (612) 624-2346, email@example.com