Tuesday, May 22, 2012
The Ellensburg sky for the week of 5/26/12
Saturday: The constellation Aquila the eagle is starting its migration across the summer evening sky this month. Aquila, marked by its bright star Altair, rises above the east horizon at about 11 p.m. Not all animal migrations are fully understood by scientists. We might be inclined to attribute bird migrations to instinct. This answer certainly did not satisfy the theologian C. S. Lewis. In his short work “Men Without Chests”, he wrote, “to say that migratory birds find their way by instinct is only to say that we do not know how migratory birds find their way”. In science (and theology), Lewis is telling us to look for real causes and not simply labels such as instinct. The cause for Aquila’s migration is the Earth orbiting the Sun. As the Earth moves around the Sun, certain constellations move into the evening sky as others get lost in the glare of the setting Sun.
Sunday: Last Sunday, the moon passed directly between the earth and the Sun resulting in a solar eclipse. For about 95% of the eclipse, the sky was cloudy in Ellensburg. However, for five minutes near the eclipse peak, the clouds thinned enough to safely view the eclipse. Here is a link to a photo taken by a CWU Astronomy Club member with her point and shoot digital camera http://goo.gl/mjxma.
Monday: Tonight’s first quarter moon is the constellation Sextans the sextant. Sextans is sort of a self-referential constellation since it is named for the astronomical instrument used to measure the positions of the stars in the constellation, itself. At 11 p.m., Mars is about a fist above the moon in the southwestern sky.
Tuesday: One week from today, Venus will pass directly between the Earth and the Sun. “Big deal, this happened in 2004”, you say dismissively. It IS a big deal because it will not happen again until 2117. Due to the tilt and wobble of Venus’ orbit, these transits, as they are called, occur eight years apart, then over a hundred years apart, then eight years apart again. Most of you reading this will have two opportunities to see Venus transit the Sun in your lifetime. People born next week will most likely have no opportunities. For a lot of general information about this transit, go to http://www.transitofvenus.org/. The CWU Astronomy Club will have a safe Venus Transit viewing event on the afternoon and evening of June 5. For the most up-to-date information about CWU Astronomy Club events such as this, go to http://www.facebook.com/CWUAC. (You don’t need to have a Facebook account to view this page.)
Wednesday: Cygnus the swan flies tonight. Deneb, the brightest star in the constellation, whose name means “tail” in Arabic, is two fists above the northeast horizon at 10 p.m. Cygnus’ wings make a vertical line one half a fist to the right of Deneb. Its head, marked by the star Albireo, is two fists to the right of Deneb. While Deneb is at the tail of Cygnus, it is at the head of the line of bright stars. It is 160,000 times more luminous than the Sun making it one of the brightest stars in the galaxy. It does not dominate our night sky because it is 2,600 light years away, one of the farthest naked eye stars. If Deneb were 25 light years away, it would shine as bright as a crescent moon. Compare that to Vega, which is 25 light years away. Vega is three and a half fists above the east-northeast horizon at this time.
Thursday: At 11 p.m., the bright star Spica is less than a half a fist and Saturn is less than a fist above the moon in the southern sky.
Friday: The month of June is named after Juno, the queen of the Roman gods and the mythological protector of the Roman state. In ancient Rome, the month began when the crescent moon was first seen in the evening sky from Capitoline Hill in Rome. If we still started months this way, June wouldn’t begin until about two weeks from now.
The positional information in this column about stars and planets is typically accurate for the entire week.