Wednesday, May 18, 2011

The Ellensburg sky for the week of 5/21/11

Saturday: There are times when people live up to their namesake. For example, Canadian figure skater Elvis Stojko lived up to the expectation of success that comes with being named after Elvis Presley. He won three world championships and two Olympic medals. The planet Venus does not live up to its namesake. 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 European Space Agency probe called Venus Express is by far the longest-lived probe. It has been sending data back to Earth for the past five years from a relatively safe polar orbit of Venus. One of the findings that surprised scientists is that Venus had active volcanoes in its recent past. For more about volcanoes on Venus and throughout the solar system, go to Venus is the brightest of the three volcano-laden planets low in the eastern morning sky. At 5 am, Venus is a half a fist held upright and at arm’s length above the east-northeast horizon. Mercury is a pinky thickness below Venus and Mars is a pinky thickness to the upper left of it.

Sunday: If you are getting up early to spot the three inner solar system planets mentioned above, you might as well look for Jupiter, as well. It is one fist above the east horizon and well to the upper right of the other three morning planets.

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: This morning’s last quarter moon is in the constellation Aquarius the water bearer.

Wednesday: 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.

Thursday: The bright summer star Antares is a half a fist above the southeast horizon at 10 p.m.

Friday: Saturn is four fists above the south horizon at 10 p.m. Scientists have discovered an electrical connection between Saturn and its moon Enceladus. The water cloud above the jets of water that spray out from Enceladus’ active volcanoes contains a charged plasma cloud. Particles from this cloud interact with Saturn’s magnetic field. For more information about this phenomenon, go to

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

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