Wednesday, July 13, 2011

The Ellensburg sky for the week of 7/16/11

Saturday: The NASA probe called Dawn will enter into orbit around the asteroid Vesta today. Launched in September 2007, Dawn will orbit Vesta for one year, mapping the surface and determining exactly what Vesta is made of. Since asteroids don’t undergo nearly as much surface change as planets, they preserve the important evidence of how the solar system was formed. By comparison, the Earth’s surface is extremely young. For more information about Dawn and Vesta, go to

Sunday: Being in a coma is a bad thing. Looking at the Coma Star Cluster is a good thing. The Coma Star Cluster is an open cluster of about 50 stars that takes up more space in the sky than 10 full Moons. It looks like a fuzzy patch with the naked eye. Binoculars reveal dozens of sparkling stars. A telescope actually diminishes from the spectacle because the cluster is so big and the telescope’s field of view is so small. The Coma Star Cluster is in the faint constellation Coma Berenices (ba-ron-ice’-ez) or Queen Berenice’s hair. Queen Berenice of Egypt cut off her beautiful hair as a sacrifice to the gods for the safe return of her husband Ptolemy III from battle. The Coma Star Cluster is about four fists held upright and at arm’s length above the west horizon at 10:30 p.m.

Monday: Mercury is less than a half a fist above the west-northwest horizon at 9:30 p.m. The slightly dimmer star Regulus is about one fist to the upper left of Mercury. This week is the best week for viewing Mercury in the evening sky for the next few months. After this Wednesday, it will move toward the Sun in the sky, soon being lost in the Sun’s glare.

Tuesday: If you want to show your loved ones a celestial sign that they should hang up their clothes, show them Brocchi's Cluster, commonly known as the Coat Hanger cluster because of its resemblance to an upside down coat hanger. The cluster is six fists above the southeast horizon at 10:30 p.m., midway between Altair and Vega, the two brightest stars in the Summer Triangle. You'll need binoculars to make out the shape. First find Altair four fists above the southeast horizon. Slowly move your binoculars up toward Vega. You will run into the coat hanger along the way. And while you are at it, put away your shoes.

Wednesday: Take a two and a half hour walk. Too long, you say? Forty-two years ago today, Neil Armstrong and Buzz Aldrin took the first ever walk by humans on another world. They spend two and a half hours setting up scientific instruments and collecting rocks for study back on Earth. Michael Collins orbited the Moon in the spacecraft the three astronauts would use to return to Earth.

Thursday: Saturn is two fists above the west-southwest horizon at 10 p.m. The star Spica, which is nearly the same brightness as Saturn, is a fist and a half to the left of Saturn.

Friday: Shaula, the star that represents the stinger of Scorpius the scorpion, is a half a fist above due south at 11 p.m.

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

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