Wednesday, February 22, 2012

The Ellensburg Sky for the week of 2/25/12

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 above the south-southwest horizon at 8 p.m. If you are looking for trouble in River City, see the Ellensburg High School production of The Music Man at 7 p.m. February 24, 25, March 2, and March 3 at Morgan Middle School. Ellensburg starts with “E” and that rhymes with “G” and that stands for great.
Venus is less than a half a fist held at arm’s length below the thin crescent Moon in the western sky at 7 p.m.

Sunday: Do you need evidence that the Moon moves significantly with respect to the rest of the sky? The Moon’s obvious change in position over the last two nights provides that evidence. Last night the Moon was right next to Venus, the brightest point of light in the night sky. Tonight the Moon is near Jupiter, the second brightest point of light in the night sky. Jupiter is about two finger widths to the lower left of the Moon. Venus and Jupiter are about one and a half fists apart from each other in the sky this week. Thus, the Moon moves about one and a half fists or 15 degrees with respect to the more distant objects in the sky from one night to the next.

Monday: 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.

Tuesday: Mars is four fists above the east-southeast horizon at 10 p.m.

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 11 p.m. to see Saturn.

Thursday: Today is Leap Day – the day when everyone leaps for joy because we have an extra day to rest. Well, not everyone leaps for joy on Leap Day. Frederic, one of the main characters in the play (and movie) The Pirates of Penzance, wished Leap Day did not exist. As an infant, Frederic was apprenticed to a group of pirates until his 21st birthday. He started to celebrate his freedom when he reached the end of his 21st year. However, the pirates read the rules differently. Frederic was born on Leap Day – February 29. The pirates want him until the 21st celebration of February 29 – when he is 84. Perhaps the pirates would have let Frederic go early if he explained the need for a Leap Day.
The Earth takes 365.24 days to orbit the Sun. Thus, each year, our calendar falls about a quarter of a day behind the Earth’s actual motion. Almost every four years, we add a day to the calendar to make up that day. You may have noticed that this correction over compensates because 4 X 0.24 = 0.96, a little less than a full day, while we add a day. In order to correct for this over compensation, the years that mark the turn of the century are not leap years unless they are divisible by 400. 2000 was a leap year. 2100, 2200, and 2300 will not be leap years. Tell your twelve-year-old to remember that on her 100th birthday.

Friday: Mercury is a fist above the west horizon at 6:30 p.m.

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

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