Thursday, February 19, 2015

The Ellensburg WA sky for the week of 2/21/15

Saturday: Venus and Mars are very close together, one and a half fists held upright and at arm’s length above the west-southwest horizon. How close together, you ask. You could not fit the largest full moon in between them. The full moon subtends an angle of about 0.5 degrees and the two planets are 0.4 degrees apart tonight.

Sunday: 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 hotter starlet”. 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. Saturn is two fists above due south at 6 a.m. The star(let) Antares is about a fist to the lower left of Saturn.

Monday: Headline from the tabloids: Earth sends robot to Mars in order to take a selfie. In January 2014, the Mars Curiosity rover took a picture of its night sky that included the Earth and moon. Both would easily be visible to the naked eye for a human standing on Mars. Since you can’t go to Mars, go to look at the picture.

Tuesday: Mercury will be as far away from the Sun in the sky as it will get this orbital cycle. This "farthest away" point is known as the planet's greatest elongation. Since Mercury is in morning sky, it is west of the Sun and this occurrence is called the greatest western elongation. This morning will be the best morning to observe Mercury for the next few weeks. Mercury is about a half a fist above the east-southeast horizon at 6:15 a.m. Over the next few weeks, Mercury will move toward the Sun in the sky. By mid April, it will be visible in the evening sky.

Wednesday: Did you know you can see stars in the daytime? Of course every smart elementary school child would answer, “the Sun is a star so, of course you can see stars in the daytime.” You, in your aged wisdom would retort, “I said stars, plural, and the Sun is only one star.” Then her even more learned middle school aged sister would note, “You can even see some of the brighter so-called night time stars during the day if you know where to look.” Today is one of those days, if you have binoculars. First, locate the moon high in the southeast sky at 5 p.m. Next, find it with your binoculars. If the moon is on the left hand side of the field of view, the star Aldebaran will be near the center. You may be able to find Aldebaran earlier but 5 p.m. is the best time because the star is high in the sky while the Sun is low in the sky.

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 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.

Friday: I hope you got your sweetie something red for Valentine’s Day two weeks ago. If not, I suggest a nice picture of the Red Valley on Mars. This January, the Mars Express probe took the first high-resolution stereo color image of Tinto Vallis, or Red Valley, the mouth of an ancient water flow on Mars. For more information and many photos of Tinto Vallis, go to Mars is one fist above the east-southeast horizon at 11 p.m.

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

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