The Ellensburg sky for the week of 5/19/12

Make plans for an astronomical fun time on Sunday from 5-7 p.m. in the CWU psychology building parking lot.

Saturday: Saturn is the orangish point of light three and a half fists held upright and at arm’s length above the south horizon at 10 p.m. The star Spica is the bluish point of light of similar apparent brightness right below it.

Sunday: Today the moon is new. Most months, that is not a big deal. This month it is a big deal because there will be an annular solar eclipse for part of the world, including part of the southwest United States, and a partial solar eclipse for the entire western United States. An annular solar eclipse occurs when the Moon, as seen from Earth, is relatively far from Earth in its orbit and not large enough to cover the Sun even though they are nearly perfectly lined up. The resulting eclipse is called an annular solar eclipse because of the ring the sunlight makes around the Moon. (The Latin word for ring is annulus.) For more information about the eclipse, go to http://goo.gl/bGSUj.

The CWU Astronomy Club is hosting a solar eclipse party today from 5-7 p.m. in the CWU psychology building parking lot just off the corner of Dean Nicholson Boulevard and Walnut Street. It is parking lot S-10 on the map found here http://goo.gl/qANHL. There will be numerous safe solar viewing opportunities and fun prizes. You should NEVER look directly at the Sun without proper protection. Even though the Moon will block about 80% of the Sun at the peak eclipse time of 6:20 p.m., the remaining light is intense enough to damage your eye.

Monday: Venus and the Moon dance low in the west-northwestern sky for the next three nights. At 9 p.m. tonight the thin crescent Moon is just barely above the horizon and is below Venus, the brightest point of light in the sky. Tomorrow night they are side-by-side. By Wednesday, the Moon is off looking for another dance partner.

Tuesday: Aquila the eagle and its bright star Altair rises at about 10 p.m. By 11 p.m., Altair is one fist above the east horizon.

Wednesday: 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”.

Thursday: Mars is four fists above the southwest horizon at 10 p.m.

Friday: 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.

The positional information in this column about stars and planets is typically accurate for the entire week. This column is also available online at http://theellensburgsky.blogspot.com/.