The Ellensburg WA sky for the week of 2/27/16

Saturday: Tonight is a great night to look for the Big Dipper. Tomorrow will be a great night to look for the Big Dipper. In fact, every night for many centuries will be great nights to look for the Big Dipper. But the Big Dipper’s shape slowly changes over many, many, many, many centuries. (Have I reached my word count yet?) Tens of thousands of years ago, it didn’t look like a dipper and tens of thousands of years from now, it will no longer look like a dipper. For a short video simulation of the changing Big Dipper, go to http://goo.gl/df1yV. For a look at the current Dipper, face northeast at 8 p.m. The lowest star, Alkaid, is two and a half fists above the horizon.

Sunday: If you ask an astrobiologist for the three most likely places to find evidence of life in the Solar System, other than Earth, they’d probably say Mars, Europa (“Didn’t they sing “The Final Countdown”?”), and Enceladus. Mars makes sense because you know scientists have sent a lot of probes there. Astronomers first discovered strong evidence of a large water ocean on Europa, a moon of Jupiter, in 1989. However, Enceladus, one of Saturn’s moons, first piqued astrobiologists’ interest a few years ago then NASA’s Cassini probe discovered jets of water containing organic materials shooting out. Two years ago, the German space agency started a project called Enceladus Explorer, EnEx for short, to collect sample from deep within Enceladus. For more information on the Enceladus mission, go to http://goo.gl/VPxzs. At 6 a.m., Mars is two fists above the south horizon and one and a half fists to the left of the Moon. Jupiter and Europa are about one fist above the west horizon. Saturn and Enceladus are two fists above the south horizon and two fists to the left of Mars. By the way, the Swedish group Europe sang “The Final Countdown”. And they were “heading for Venus” in the song, not to the worlds of the outer Solar System. Venus is just above the east-southeast horizon.

Monday: It is often said that Earth is a water world because about 70% of the Earth’s surface is covered by water. What would it look like if all that water on the surface were gathered up into a ball? That “ball” would be about 700 km in diameter, less than half the diameter of the Moon. The Astronomy Picture of the day shows us right here http://goo.gl/4wXLM.

Tuesday: In this busy world, it is important to know what time it is. We have many devises that give us the time. A phone. A computer. A watch. But who has time to build a phone, computer or even a watch. Not you. But everyone has enough time to build a simple Sun Clock. All you need is a pencil, a compass and a print out of the clock template. Go to https://www.exploratorium.edu/science_explorer/sunclock.html for more information.

Wednesday: Jupiter is one fist above due east at 7 p.m.

Thursday: Avast ye matey. Swab the poop deck. Pirates love astronomy. In fact, the term “poop” in poop deck comes from the French word for stern (poupe) which comes for the Latin word Puppis. Puppis is a constellation that represents the raised stern deck of Argo Navis, the ship used by Jason and the Argonauts in Greek mythology. Argo Nevis was an ancient constellation that is now divided between the constellations Puppis, Vela and Carina. The top of Puppis is about a fist and a half to the left of the bright star Sirius low in the southern sky at 9 p.m. Zeta Puppis, the hottest, and thus the bluest, naked eye star in the sky at 40,000 degrees Celsius is near the uppermost point in Puppis.

Friday: Astronomers estimate that asteroid 2013 TX68 will pass “close to” Earth. How close? It could be as close as 11,000 miles – just about one Earth-diameter away. It could be 9 million miles – about one fifth the distance to Mars. The uncertainty is so large because we don’t know enough about its orbit. Thankfully, this close encounter will help astronomers pin it down so we know the chances of being struck by 2013 TX68 in the future. For more information about 2013 TX68 and other near Earth asteroids, go to http://goo.gl/6kf8bo.

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.