Starwatch: May 2013
After the April we've had, May has got to have clearer skies. Let's hope so, anyway.
We'll need those clear skies to see Jupiter, Venus and Mercury perform an intricate dance during the second half of May. Jupiter, in the west, is dropping from the sky as Earth leaves it behind in the orbital race; meanwhile, Venus and Mercury are climbing into the evening sky as they catch up to Earth. Mercury, being closer to the sun, is faster and outstrips Venus.
The dance begins with Jupiter descending into the sun's afterglow as Venus comes up to meet it. Then, in the last week of the month, Mercury pops up and becomes the highest of the three planets by month's end. Try to get out the evening of the 26th, when the three will form a compact trio that fits easily within a binocular field.
Saturn, still bright after being lapped by Earth in late April, comes out in the east after nightfall and follows Spica, the brightest star in Virgo, across the sky. Above the ringed planet, brilliant Arcturus leads its kite-shaped constellation, Bootes, the herdsman, on its nightly journey. These three objects form a rather long, thin triangle with Arcturus at its apex.
The Eta Aquarid meteor shower is expected to peak in the predawn hours of the 6th, but plenty of meteors will fly for a few days before and after that date. A waning moon will be up, but shouldn't interfere much, especially on and after the 6th. Meteors will radiate from a point near the Water Jar of Aquarius, which rises a couple of hours after midnight in May. Eta Aquarid meteors are typically fast and bright, and often leave persistent trails.
In the north, the Big Dipper is very high during evening hours and "spills its water" down toward the Little Dipper. In the southwest, Leo, the lion, is also high, its head an upright but backward question mark of stars anchored by bright Regulus.
Between Leo and the bowl of the Big Dipper, try to find three evenly spaced pairs of stars known as the Three Leaps of the Gazelle. The gazelle leaps along a line running northwest from a spot just above Leo's hindquarters. These three pairs of stars are also identified as three feet of Ursa Major, the great bear--the constellation that includes the Big Dipper.
The Milky Way sits on the horizon in every direction during evenings in May. But in the early morning hours it lifts up in the east and moves westward behind the spring constellations.
To Algonquin Indians, May's full moon was the full flower moon, corn planting moon or milk moon. The moon becomes full at 11:25 p.m. CDT on the 24th, having risen, round and beautiful, in daylight less than three hours earlier. At 11:11 p.m. the moon just barely grazes the northernmost part of Earth's penumbra, or light outer shadow, but this event--which is, technically, an eclipse--will not be noticeable.
The University of Minnesota offers public viewings of the night sky at its Duluth campus. For more information and viewing schedules, see the Marshall W. Alworth Planetarium website at www.d.umn.edu/planet.