May 2006

by Deane Morrison

In May the night sky shrinks at both ends from the relentless onslaught of the climbing sun. But it takes more than that to dim the brilliance of Jupiter, the king of planets. Earth glides straight between Jupiter and the sun on the 4th, an event called opposition because it places the giant planet directly opposite the sun in the sky. At that time Jupiter will be at its biggest and brightest for the whole year. After rising around sunset, its yellowish globe transits the heavens east of the bright star Spica and west of the claws of Scorpius.

Not to be outdone, Saturn and Mars stage their own pas de deux even as Earth's orbital motion carries them toward the western horizon. Saturn, a relatively sluggish outer planet, cleaves to the Beehive star cluster of Cancer while speedier Mars, in Gemini, rushes eastward toward its ringed companion. The planets continue like this through June, when Mars will sweep through the Beehive--a sight not to be missed.

Over in the predawn sky, Venus glows brightly but never gets very high. Our sister planet, though beautiful, has long been known to be searingly hot and inhospitable to life. In mid-April, the European Space Agency's Venus Express spacecraft sent back images of sulfuric acid clouds swirling around the planet's south pole, driven by 220 mph winds. The spacecraft, which had gone into orbit around Venus only the day before, may help researchers find the origins of both the clouds and the wind, plus other clues to the evolution of Earth's closest planetary neighbor.

The full moon of May arrives just before 2 a.m. CDT on the 13th. Algonquin Indian tribes called it the flower moon, the corn planting moon or the milk moon. It rises the night of the 12th close to Jupiter. On the 24th, its waning crescent passes Venus. A new moon arrives at 12:26 a.m. on the 27th, and a waxing crescent visits Mars on the 30th. The moon ends the month by appearing above the Beehive and Saturn on the 31st.

Comet Schwassmann-Wachmann 3 shoots across the sky early in the month. Discovered in 1930, the comet split into several pieces during a pass in 1995. This time around, it may--possibly--be bright enough to see with the naked eye or at least a good pair of binoculars. It appears just southwest of the bright star Vega, in Lyra, on the 7th, then hurtles southeastward across the Milky Way and through the Summer Triangle of stars (which includes Vega), below the southwestern corner of the Great Square of Pegasus and into Pisces. It makes its closest approach to Earth on the 12th, just before it exits the Milky Way. Unfortunately, the farther east it goes, the later it rises, and a fairly bright waxing moon dogs the comet all week. It may be best to look on the 1st or 2nd, when the moon is less bright. You can see the comet's path through the stars by visiting http://www.aerith.net/comet/catalog/0073P/2006.html.

The Eta Aquarid meteor shower peaks on the mornings of the 4th through the 6th. Meteors from this minor shower radiate from the Water Jar of Aquarius, which will be in the eastern sky at sunrise. Look between about 3:30 and 5 a.m., after the Water Jar has risen but before dawn comes.

During May the sun gets nearly as high as in June. Even by May Day the sun's rays can cause sunburn in sensitive people. Therefore, if you're prone to sunburn, May Day is none too soon to start taking precautions.