Thursday, April 26, 2018

The Ellensburg WA sky for the week of 4/28/18

Saturday: As the rock group Journey once thought of singing, “Wheel in the sky keeps on turnin’. Know where the Dipper’ll be tomorrow.” Every night, the Big Dipper and Cassiopeia make a wheel in the sky that turns around the North Star in a counter clockwise direction. Every year on May 3 at 10 p.m., the Big Dipper is straight overhead and W-shaped Cassiopeia is low on the northern horizon. Every year on May 4 at 10 p.m., the Big Dipper is straight overhead and W-shaped Cassiopeia is low on the northern horizon. Every year on May 5 at 10 p.m., the Big Dipper is straight overhead and W-shaped Cassiopeia is low on the northern horizon. Every year on May 6 at 10 p.m., well, you get the idea. Of course, there are subtle charges in the position from night to night. Each northern constellation moves about one degree counter clockwise from one night to the next. But this is not going to change their position in the sky drastically over a few days. So, if you know where the Big Dipper is tonight, you DO know where it’ll be tomorrow. If you are really struggling to understand this concept, Don’t Stop Believin’ in yourself. Just keep studying Faithfully. 

Sunday: Mercury will be as far away from the Sun in the sky as it will get this orbital cycle. This "farthest away" point is known as the planet's greatest elongation. Since Mercury is in morning sky, it is west of the Sun and this occurrence is called the greatest western elongation. This morning, Mercury is just above due east at 5:30 a.m. Over the next few weeks, Mercury will move toward the Sun in the sky. By late June, it will be visible in the evening sky. 

Monday: Winter must be over because the winter constellations are becoming less visible. Orion is setting in the west starting at about 9 p.m. At this time, Orion’s belt is one fist above the west-southwest horizon and Betelgeuse is nearly two fists above the west horizon. By mid-May, Orion will be lost in the glare of the Sun. 

Tuesday: Venus is one and a half fists above the west horizon at 9 p.m. Jupiter has just risen over the east-southeast horizon. By 11 p.m., Jupiter is nearly two fists above the southeast horizon. It looks so peaceful up there. But life is not peaceful for Jupiter. According to a recent study by astronomers, Jupiter gets hit by a 5-20 meter in diameter asteroid 10 to 65 times a year. For comparison, the object that exploded over the Russian city of Chelyabinsk in 2013 was 20 meters in diameter. Earth gets hit by a 20-meter asteroid about once every 50 years. For more information, go to 

Wednesday: At 5 a.m., Saturn is two fists above due south and Mars is one and a half fists to the left of Mars. 

Thursday: The CWU Physics Department and the College of the Sciences is hosting its monthly First Saturday planetarium show this Saturday from noon to 1 pm. CWU physics professor Tony Smith will honor mothers with a presentation about mothers in the night sky. It's certainly not a man's world up there! The show is free and open to all ages. There will be a show at noon on the first Saturday of every month hosted by different CWU astronomers and astronomy educators. The planetarium is room 101 in Science Phase II, just off the corner of 11th and Wildcat Way, H-11 on the campus map found at 

Friday: The Eta Aquarid meteor shower peaks tonight and tomorrow morning. But since this meteor shower has a fairly broad peak range, there will be many more meteors than in the typical pre-dawn sky throughout the month of May. Meteor showers are named after the constellation from which the meteors appear to originate. The meteors appear to come from a point in the constellation Aquarius near the star Eta. This point is about one fist above the east horizon at 4 a.m. The Moon is in the waning gibbous phase and its light will obscure the dimmer meteors. So you could be rewarded with many bright, fast meteors. The Eta Aquarid meteors slam into the Earth at about 40 miles per second. They often leave a long trail. The Eta Aquarid meteors are small rocks that have broken off Halley’s Comet. For more information about the Eta Aquarids, go to 

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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