Thursday, April 2, 2015
The Ellensburg WA sky for the week of 4/4/15
Saturday: The first day of spring was March 20. The most recent full moon was last week. That means tomorrow is Easter. The standard way to determine the date of Easter for Western Christian churches is that it is the first Sunday after the full moon that occurs on or after the vernal equinox, also known as the first day of spring. Of course, the other standard way is to look for the date of church services celebrating the resurrection of Jesus. There is no Bible story of an “Easter star”. If there were, Spica would be a pretty good choice. The name Spica comes from the Latin “spica virginis” which means “Virgo’s ear of grain”. Spica represents life-giving sustenance rising after a long winter just like the risen Jesus represents life-giving redemption to Christians. Spica is a half a fist held upright and at arm’s length above the east-southeast horizon at 9 p.m., just to the lower right of the Moon. For an algorithm on how to calculate the exact date of Easter for any year, go to http://goo.gl/gFnepP.
Sunday: Jupiter is six fists above due south at 9 p.m.
Monday: At 8:30 p.m., Mars is a half a fist above the west-northwest horizon and Venus is two and a half fists above the west horizon.
Tuesday: Vega is one fist above the northeast horizon at 10:30 p.m.
Wednesday: So far this week, I have written about Venus, Mars, and Jupiter. Do you like these planets or does another planet really catch your fancy? If you’d like to know what most people’s favorite planet is, go to http://www.pbs.org/wgbh/nova/pluto/favorite.html and click on “Launch Interactive”. The public TV special called “The Pluto Files” has set up a website in which astronomers give a 30-second pitch for why a certain planet is their favorite. After listening to the pitch, you may vote for your favorite planet. Of course, you may also do what most people do for political elections: vote for the candidate with the best name or the one with the most interesting campaign slogan. So whether you carefully consider each planet or simply “Swoon for Neptune”, “Jump for Jupiter”, or “Pick Uranus”, go to “The Pluto Files” and vote. Saturn will be holding a campaign rally at 6 a.m., two fists above the south-southeast horizon.
Thursday: Two weeks ago, I asked you to watch the bright star Deneb to observe how its time at due north changes from night to night. It reached due north at 10:18 p.m. two Thursdays ago. Tonight, it reaches due north at 9:23 p.m., 55 minutes earlier. As the Earth revolves around the Sun, it also rotates on its axis. (Wow Bruce, really? We learn so much from you!) Because it does both motions counterclockwise as viewed from above the Earth’s North Pole, any given spot on Earth faces the distant stars a little bit earlier each day than that spot faces the Sun. Based on the specific rotational and revolution speed, it amounts to three minutes and 56 seconds earlier each day. That’s 27.5 minutes earlier each week and… wait for it… wait for it… 55 minutes earlier every two weeks. Depending on where you live, those due north times may be off by a few minutes. But the two-week difference will be the same no matter where you live. (I apologize for my smart aleck statement earlier. You DO teach us a lot.)
Friday: It you didn’t run the Yakima River Canyon Marathon two weeks ago, satisfy that marathon craving by attending a virtual Messier Marathon. Charles Messier (pronounced messy a) was an 18th century French astronomer best known for his catalog of 110 nebulae and star clusters. Amateur astronomers love to find as many of these as they can in one night. During the online Messier Marathon, you’ll see the images broadcast on the Internet. The fun starts this morning at 11:30 a.m. Pacific Daylight Time (when astronomers on the nighttime side of Earth point their telescopes towards interesting celestial objects). For more information, go to http://goo.gl/DWnhHL.
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 http://nightsky.jpl.nasa.gov/planner.cfm.