Thursday, September 22, 2011

The Ellensburg sky for the week of 9/24/11

Saturday: “You know Aries and Cancer and Draco and Libra. Leo and Pisces and Virgo and Hydra. But, do you recall, the pointiest asterism of all? Triangulum, the three sided asterism, had a very pointy edge….” Sorry. Some stores have started putting up their Christmas decorations and that has put me in the mood to modify some Christmas songs. Anyway, Triangulum is a small constellation between the more prominent Andromeda and Aries. Its main feature is a skinny triangle oriented parallel to and nearly four fists held upright and at arm’s length above the east horizon at 10 p.m.

Sunday: Regulus is a fist to the upper left of the Moon at 6 a.m.

Monday: Did you time the exact length of the day and night last Wednesday on the first day of autumn? They were not equal in duration. Many people think that the day and night are the same duration on the autumnal equinox. The day is a little longer than the night for two reasons. First, the Sun is an extended object so even when the middle part has set, the upper half is still above the horizon lighting the sky. The second, and more influential reason, is that the atmosphere acts like a lens, bending light from the Sun above the horizon when the Sun is really still below the horizon. Day and night are closest in duration today.

Tuesday: This is the best week of the year to see Uranus, the seventh planet from the Sun. But you’ll need binoculars to find it. First, find Deneb Kaitos, a star one fist above the southwest horizon at 10 p.m. This star, whose name means “whale’s tail”, is about the same brightness as the Big Dipper stars. Another fist up is a reddish star called Iota Ceti. Put this star in the bottom of your binoculars’ field of view. At the top of the field of view should be a skinny, upright rectangle. Move the upper left corner of this rectangle to the lower right hand portion of your binoculars’ field of view. Uranus is a bluish dot near the middle of the field of view.

Wednesday: The west-southwest horizon is crowded just after sunset. Spica is about a fist to the upper right of the Moon at 7 p.m. The much brighter Venus is another fist to the right of Spica. Finally, Saturn is about a finger width above Venus.

Thursday: The cloudy season is coming to Ellensburg. Don’t feel bad. According to three astronomers, it is always cloudy season on HD 85512b, a newly discovered planet orbiting the star called… wait for it… wait for it… called HD 85512. These astronomers developed a method to estimate the cloud cover on planets orbiting distant stars. They think HD 85512b may be cloudy enough to have liquid water on its surface even though it is fairly close to its host star. While the presence of surface water does not guarantee finding life, it is a critical component. For more information, go to

Friday: Jupiter is two fists above the east horizon at 10 p.m.

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

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