Wednesday, November 21, 2012

The Ellensburg sky for the week of 11/24/12

Saturday: This week brings a special treat to the morning sky. Two of the most interesting planets to look at with binoculars or a small telescope dance past each other in the sky. At 6 a.m. tomorrow morning, they are about one fist held upright and at arm’s length above the east-southeast horizon. Saturn is about a thumb-width to the lower left of the much brighter Venus. With binoculars, you should be able to find Saturn’s largest moon, Titan, about eight Saturn-diameters to the lower left of Saturn.

Sunday: Most constellations don’t look like the object their name refers to. Most constellations don’t have such a simple to object to emulate as Triangulum. As you probably guessed, Triangulum is shaped like a princess. Wait…. Just a second…. I read my book wrong. Triangulum is shaped like a thin isosceles triangle. Mothallah is the only named star in the constellation. In Latin this star is called Caput Trianguli, the head of the triangle. Triangulum is seven fists held upright and at arm’s length above the south horizon at 9 p.m. It is pointing down and to the right with Mothallah being the southernmost star at this time of night. The Triangulum Galaxy can be seen with binoculars about a half a fist to the right of Mothallah.

Monday: Venus and Saturn are about as close together as they are going to get in the morning sky at 6 a.m. They would both fit into the field of view of a small backyard telescope at less than a degree apart. While you are looking through your binoculars or small telescope, look at Saturn’s rings. They look so delicate. But they may have formed by violently shredding the outer envelop of an ancient moon before it collided with Saturn. For more information about Saturn’s rings, go to

Tuesday: Have you been shopping all weekend? Do you need an evening sky break? You deserve a big reward so make it a double. A Double Cluster, that is. The Double Cluster, also known as h and Chi Persei, consists of two young open star clusters in the constellation Perseus. Of course, young is a relative term as these clusters are about 13 million years old. Each cluster is spread out over an area about the same size as the full moon. To the naked eye, the Double Cluster shines with a steady, fuzzy glow. Binoculars resolve dozens of individual stars in the clusters. The Double Cluster is six and a half fists above the northeast horizon at 7 p.m., about a fist below the sideways “W” of Cassiopeia.

Wednesday: Well, it is late November. It is time to set the beaver traps before the swamps freeze so you have a supply of warm winter furs. You must be getting ready to do that because the November full moon is known as the full beaver moon. Or maybe you shop for winter coats at a fine Ellensburg business (shop local). If that is the case, you may think the name full beaver moon came about because the beavers, themselves, are preparing for winter. Setting their human traps for… I guess I shouldn’t continue that thought.

Thursday: Jupiter and the moon trek through the sky together tonight. They rise at about 4:30 p.m., just as the Sun sets. Look for them in the east-northeast sky. If you want an observing challenge, see if you can spot the bright star Aldebaran before 5 p.m. It is to the lower right of the moon. In fact, observing the relative positions of Jupiter, the moon, and Aldebaran throughout the night will show you how the different objects appear to move with respect to each other. Because Aldebaran is so far away, its observable motion is completely due to the Earth’s rotation. Jupiter, as one of the outer planets, moves slightly with respect to the background stars from night to night. If you carefully measured the distance between Jupiter and Aldebaran in the sky each night, you’d notice a change. The moon, being our nearest neighbor and being in orbit around us, moves noticeable with respect to the background stars throughout the night. By 9 p.m., the moon and Jupiter are twice as far apart from each other as they were at 5 p.m.

Friday: Do you like to look in a nursery and say “it’s a boy” or “it’s a girl”? Not me. I say, “It’s a star”. Of course, I like looking into a stellar nursery – a star forming region such as the Orion Nebula in the middle of Orion’s sword holder. The Orion Nebula looks like a fuzzy patch to the naked eye. Binoculars reveal a nebula, or region of gas and dust, that is 30 light years across. The center of the nebula contains four hot “baby” stars called the Trapezium. These hot stars emit the ultraviolet radiation that causes the Nebula’s gas to glow. The Orion Nebula is three fists above the southeast horizon at 11 p.m.

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

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