Thursday, May 13, 2010

The Ellensburg sky for the week of 5/15/10

Saturday: Venus is a half a fist held upright and at arm’s length to the upper left of the Moon at 9 p.m. While the planet was named for the Roman goddess of love and beauty, it is not a loving place. The surface of the planet is 460 degrees Celsius (860 degrees Fahrenheit), hot enough to melt lead. The barometric pressure on the surface is over 90 times greater than on Earth’s surface. Most missions to Venus have failed either before sending back data or after only a few minutes of sending back data. Not a very neighborly attitude from our nearest planetary neighbor. The next planned Venus explorer is the Japanese mission called Akatsuki, still in development. For an effective introduction to Venus and many other significant solar system objects including the eight planets, Pluto and the Sun, go to

Sunday: Spica, the brightest star in the constellation Virgo, is known as the Horn Mansion one of 28 mansions, or constellations, in the Chinese sky. Spica is about three fists above the south horizon at 11 p.m.

Monday: Late spring and early summer is a good time to look for star clusters. Last week, you learned about M3, the third object cataloged by French astronomer Charles Messier over 200 years ago. One of the best clusters is the globular cluster in the constellation Hercules, also called M13. (Hummm. Guess what number that object is in Messier’s catalog.) Globular clusters are compact groupings of a few hundred thousand stars in a spherical shape 100 light years across. (For comparison, a 100 light year diameter sphere near out Sun would contain a few hundred stars.) The globular cluster in Hercules is six fists above due east at 11 p.m. First find Vega, the bright bluish star about four fists above the east-northeast horizon. Two fists to the upper right of Vega is a keystone shape. Aim your binoculars at the two stars that form the uppermost point of the keystone. The globular cluster is one third of the way south of the uppermost star on the way to the rightmost star of the keystone. It looks like a fuzzy patch on the obtuse angle of a small obtuse triangle. If you don’t know what an obtuse angle is, you should not have told your teacher, “I’ll never need to know this stuff”.

Tuesday: When it is sitting low in the western sky, many people mistake the star Capella for a planet. It is bright. It has a slight yellow color. But, Capella is compelling on its own. It is the fourth brightest star we can see in Ellensburg. It is the most northerly bright star. It is a binary star consisting of two yellow giant stars that orbit each other every 100 days. At 10 p.m., Capella is two fists above the northwest horizon. If you miss it tonight, don’t worry. Capella is the brightest circumpolar star meaning it is the brightest star that never goes below the horizon from our point of view in Ellensburg.

Wednesday: Mars, looking like a bright orange star, is about a half a fist above the Moon at 10 p.m. They are four fists above the west-southwest horizon.

Thursday: The first quarter Moon is in the constellation Leo the lion, about a half a fist below the bright star Regulus.

Friday: Jupiter is two fists above the east-southeast horizon at 5 a.m.

The positional information in this column about stars and planets is typically accurate for the entire week.

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