Thursday, August 24, 2017

The Ellensburg WA sky for the week of 8/26/17

Saturday: Arcturus is four fists above the west-southwest horizon at 10:30 p.m. This star, whose name means bear watcher, is the brightest in the sky’s northern hemisphere. It follows Ursa Major, the Great Bear, around the North Star. Arcturus is the closest giant star to Earth. It is one of the few stars whose diameter can be measured directly rather than being inferred from its density and mass, which, themselves are derived from other parameters.

Sunday: Have you ever gone to a family reunion, looked around and asked, “How in the world are we related to each other?” Astronomers look around the Solar System and wonder if there is life anywhere else that we are related to. The Mars Science Laboratory landed on Mars in 2012 to investigate whether it ever had conditions favorable for life. The Venus Express studied the atmosphere of Venus from 2006 to 2014. The Cassini Mission continues to study the plume of complex organic chemicals streaming from Saturn’s moon Enceladus. NASA and the European Space Agency are planning missions to study Europa, the Jovian moon with an ice-covered ocean. And many astronomers consider the methane haze in the atmosphere in Saturn’s moon Titan similar to that of the early Earth. To learn more about the search for life in the Solar System and beyond, go to While you won’t see anyone waving back, you can see Mars and Venus in the early morning sky. At 5:45 a.m., Mars is a half a fist above the east-northeast horizon and Venus is two fists above the east horizon.

Monday: What did you do last Monday? Hopefully, many of you watched the solar eclipse safely. Many professional and citizen scientists, including some from Central Washington University, acquired valuable eclipse data. Read about a summary of three projects here: For more information about CWU’s project, go to

Tuesday: Saturn is a half a fist to the left of the Moon in the southwest sky at 10 p.m.

Wednesday: Deneb is nearly straight overhead at 11:30 p.m. When you look at Deneb, you are seeing light that left Deneb about 1,800 years ago.

Thursday: All stars rotate. Our Sun takes a little less than an Earth month to make one rotation. Astronomers have started to study the relationship between mass, stellar rotation, and planetary formation by aiming NASA’s Kepler space telescope toward the Pleiades open star cluster. All 1,000 stars in this group is nearly the same age, 125 million years old. Since all of the stars are the same age and formed from the same set of materials, astronomers have the ideal “laboratory” to isolate the role star mass plays on star rotation and evolution. Read more about the findings at See the Pleiades for yourself, one fist above the east-northeast horizon at 11:30 p.m.

Friday: Florence + the Machine sang, “Dog Days are Over”. Today, Florence the large near-Earth asteroid will be singing “Nice to get Close to you, Earth”. The 2.7-mile diameter asteroid will pass within about 18 earth-Moon distances. Even though 2.7 miles in diameter seems small compared to the sixe of astronomical objects we are familiar with such as the Moon, Mars, and the Death Star, it is the largest asteroid to pass this close to Earth since the NASA program to detect near-Earth asteroids began.

The positional information in this column about stars and planets is typically accurate for the entire week. For up to date information about the night sky, go to

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