Wednesday, February 20, 2013

The Ellensburg sky for the week of 2/23/13

Saturday: An astronomy version of The Music Man might go something like this: “Oh, we got trouble, in the river constellation. With a capital “T” and that rhymes with “B”, and that stands for bright.” And bright does NOT describe the river constellation called Eridanus, at least as seen from the northern United States. Eridanus is a river of dim stars that winds beneath the feet of Orion and off to the lower right. Orion is four fists held upright and at arm’s length above the south-southwest horizon at 8 p.m.

Sunday: It’s getting dark. The last remnant of twilight has disappeared. Suddenly, you notice a large softly radiant pyramid of light in the western sky. The base of this ghostly triangle is along the west horizon and the peak stretches two or three fists above the horizon. It is not really a ghost. It is an effect called the zodiacal light. This light comes from sunlight reflecting off dust grains in our solar system. The effect is the most visible when the band of constellations called the zodiac makes a steep angle with the horizon. You need a clear dark sky with no haze or light pollution to see the zodiacal light. At its brightest, the zodiacal light rivals the light of the central Milky Way. Look for the ghostly patch after twilight for the next few weeks.

Monday: Tonight’s full moon is in the constellation Sextans the sextant. Sextans is a faint constellation below Leo the lion. Its most noticeable feature is a triangle just to the right of the moon at 10 p.m. Sextans is one of seven constellations proposed by Polish astronomer Johannes Hevelius in the 1600s. He used a sextant to measure star positions and decided to honor the tool with a constellation.

Tuesday: 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 in the south-southwest sky at 10 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.

Wednesday: If the National Enquirer was around in Galileo’s day, it may have featured the headline: “Saturn has love handles; Opis leaves him for a much thinner Mars”. When Galileo first observed Saturn through a telescope, he reported objects that looked like bulges on either side of Saturn’s midsection. He was actually seeing Saturn’s rings through less than ideal optics. Look one fist above the east-southeast horizon at midnight to see Saturn.

Thursday: By now you have probably heard or read about the meteor that exploded over Russia on February 15. If not, you no longer have to pour over dozens of articles. Just go to Wikipedia like thousands of students do every day:

Friday: The space shuttles have been retired. But that does not mean NASA is not thinking about the future of space flight. Here is a small NASA poster summarizing the future of American Human spaceflight: While NASA is not planning on sending people to Jupiter, you may visit it with your eyes, five and a half fists above the southwest horizon at 8 p.m.

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

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