Wednesday, December 8, 2010

The Ellensburg sky for the week of 12/11/10

Saturday: Grandfather Cuts Loose the Ponies on a hill overlooking Vantage, Washington. And the sky cuts loose three horses of its own: Pegasus, the flying horse; Equueus, the little horse; and Monoceros, the unicorn. The Great Square of Pegasus is easiest to find. The center of the square is nearly six fists held upright and at arm’s length above the southwest horizon at 8 p.m. Equueus is about two fists to the right of the Moon and Monoceros is just rising due east.

Sunday: Jupiter is four fists above the south horizon at 7 p.m.

Monday: The Geminid meteor shower peaks at 3 a.m. tomorrow morning but will remain highly active throughout the night. Meteor showers are named after the constellation from which the meteors appear to originate. These meteors appear to come from a point in Gemini the twins. This point is about three fists held upright and at arm’s length above the east-northeast horizon at 9 p.m. tonight. You can follow this point throughout the night as it will remain near the bright star Castor, the right hand star of the “twin” stars Pollux and Castor. This shower is typically one of the best ones of the year producing bright, medium speed meteors with up to 80 meteors per hour near the peak. The Moon will have set for most of the night so the sky will be very dark meaning good viewing conditions. Yahoo! News is calling this the best meteor shower of 2010.
Most meteor showers occur when the Earth passes through the orbital trail of a comet. The broken off comet fragments collide with the earth and burn up in the atmosphere. Astronomers had searched for a comet source for this shower since 1862 when the shower was first observed. Finally, in 1983, astronomers discovered the object that created the fragments that cause the meteor shower. To their surprise, it was a dark, rock that looked like an asteroid, not a shiny icy comet. Astronomers named this object Asteroid 3200 Phaethon. But, they still don’t know if it an asteroid or if it is a comet with all of its ice sublimated away by many close passes by the Sun. For more information about 3200 Phaethon, go to

Tuesday: On these cold mornings, it is difficult to get going. You just want to plop into a chair and sit still. But, are you really sitting still? You’re moving at about 700 miles per hour due to the rotation of the Earth on its axis and 66,000 miles per hour due to the revolution of the Earth around the Sun. If that’s not enough, the entire solar system is orbiting the center of the galaxy at a whopping 480,000 miles per hour! So while you may be sitting still with respect to your living room (and all of the over achievers in your house), you are NOT sitting still with respect to the center of the galaxy. For more information about this concept, go to

Wednesday: Venus is two and a half fists above the southeast horizon. Even though the dawn sky is well lit, Venus is still bright enough to be seen. Some people call Venus the “morning star”. I call it the “late sleepers’ planet”.

Thursday: When you were growing up, you may have heard “Don’t make waves.” The red supergiant star Betelgeuse must not have listened. According to data from the Japanese Akari satellite, Betelgeuse creates a shockwave as it moves through the surrounding cloud of gas and dust. If viewed through a telescope sensitive to infrared radiation, this shockwave would appear to be the size of the full Moon as seen from Earth. Betelgeuse is four fists above the southeast horizon at 10 p.m.

Friday: Saturn is nearly four fists above the south-southeast horizon at 7 a.m. If you don’t want to get up so early, stay up until 2 a.m. and look for Saturn less than a fist above the east horizon.

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

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