Wednesday, February 16, 2011

The Ellensburg sky for the week of 2/19/11

Saturday: This President’s Day weekend, let’s remember Abraham Lincoln: 16th president, country lawyer, man on the penny, and astronomer. Astronomer? Well, maybe not an astronomer, but someone who used observational evidence from the sky to solve a problem. In 1858, Lincoln defended Duff Armstrong, a family friend who was accused of murder. The prosecution thought they had a strong case because their primary witnesses claimed to have observed the killing by the light of the nearly full moon. Let’s listen in on the trial courtesy of the 1939 film, Young Mr. Lincoln.
Lincoln: How’d you see so well?
Witness: I told you it was Moon bright, Mr. Lincoln.
Lincoln: Moon bright.
Witness: Yes.
(Dramatic pause as Lincoln reaches for something)
Lincoln: Look at this. Go on, look at it. It’s the Farmer’s Almanack (sic). You see what it says about the Moon. That the Moon… set at 10:21, 40 minutes before the killing took place. So you see it couldn’t have been Moon bright, could it?
Lincoln used the known information about Moon rise and set times for August 29, 1858 as evidence in a trial. You may confirm Lincoln’s findings on the Moon set time by going to, the US Naval Observatory website, and filling out Form A. For more information about Lincoln’s “almanac trial”, go to

Sunday: The sky provides an effective lesson in geometry and in relative motions tonight. At 11 p.m., the moon, Saturn, and the bright star Spica form a small right triangle one and a half fists held upright and at arm’s length above the southeast horizon. Saturn is to the upper left of the moon and Spica is to the lower left. By 6 a.m. tomorrow morning, this triangle as moved across the sky to about two fists above the southwest horizon. Saturn is now to the upper right of the moon and Spica is to the upper left. These are simply changes in their position in the sky due to the rotation of the Earth. But, because the moon is very close to the Earth, in an astronomical scale, we can observe the moon’s actual motion with respect to more distant objects. Thus, you will notice that the triangle tonight has a slightly different shape than the triangle tomorrow morning because the moon has moved eastward toward Spica in the sky.

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: Venus is a little less than one fist above the southeast horizon at 6 a.m.

Wednesday: Sirius, the brightest star in the nighttime sky, is two and a half fists above the south horizon at 9 p.m.

Thursday: Jupiter is a little more than one fist above the west horizon at 7 p.m. By mid-March, Jupiter will be lost in the glare of the Sun. But that will not make Jupiter any less interesting. Jupiter’s dark Southern Equatorial Belt (SEB) disappeared for most of 2010, probably covered by lighter colored ammonia clouds in Jupiter’s upper atmosphere. But recent photographs taken using an infrared wavelength camera show that the ammonia clouds may be starting to part, revealing the SEB once again. For more information, go to

Friday: Have you been to outer space lately? Neither have I. But the iron meteorite slice just acquired by the Central Washington University Astronomy club has. It made the trip from the inner Solar System asteroid belt long ago, landed on a farm near Uruaçu, Brazil in 1992 and now resides in a display case near the middle of the first floor in Lind Hall on the CWU campus. Thanks to NASA and the Night Sky Network for providing this slice of a coarse octahedrite meteorites are composed primarily of nickel-iron alloys

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

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