Thursday, January 11, 2018
The Ellensburg WA sky for the week of 1/13/18
Saturday: Who can forget that memorable song by Three Dog Constellations Night, “The sky is black. The stars are white. Together we learn to find the light.” Well, maybe it didn’t go like that. Which is good. Because not all stars are white. Most stars are too dim to notice a color. But, two of the stars in the constellation Orion provide a noticeable contrast with each other. Betelgeuse, five fists held upright and at arm’s length above the south horizon at 10:30 p.m. is a red giant. Rigel, the bright star about two fists to the lower right of Betelgeuse, is a blue giant.
By the way, the three dog constellations are Canis Major, the greater dog, found one and a half fists to the lower left of Orion; Canis Minor, the lesser dog, found two and a half fists to the left of Betelgeuse; and Canes Venatici, the hunting dogs, found low in the northeast sky. Canis Major contains Sirius, the brightest star in the nighttime sky.
Sunday: On these cold mornings, it is difficult to get going. You just want to plop into a chair and sit still. But, are you really sitting still? You’re moving at about 700 miles per hour due to the rotation of the Earth on its axis and 66,000 miles per hour due to the revolution of the Earth around the Sun. If that’s not enough, the entire solar system is orbiting the center of the galaxy at a whopping 480,000 miles per hour! So while you may be sitting still with respect to your living room (and all of the over achievers in your house), you are NOT sitting still with respect to the center of the galaxy. For more information about this concept, go to http://goo.gl/lPVPS. Before you barf from all of that motion, go outside at 7 a.m. and observe the planets. Jupiter, the brightest point of light in the sky, is two and a half fists above the south horizon. Reddish Mars is a half a fist to the lower left of Jupiter. Saturn and Mercury are each a little less than a half a fist above the southeast horizon. Mercury is the brighter of the two and is to the lower left of Saturn.
Monday: Vega is one fist above the northwest horizon at 7 p.m.
Tuesday: Have you ever planned a vacation to a place because it was supposedly the up-and-coming locale? Then, when the vacation time finally arrives, you find out the place doesn’t live up to its billing? A little over five years ago, astronomers discovered that the star Tau Ceti, one of our closest neighbors at 12 light years away, has five planets. They claimed two of the planets are in the so-called habitable zone where the temperature is just right for having liquid water. Time for a va-ca-tion! Well, not so fast. Astronomers have only a lower limit to the planet masses so they may be too massive for complex life to form. And the Tau Ceti system has ten times as much mass in dist and rocks as our own solar system. So you’ll want to do some research before you travel there. Tau Ceti is two and a half fists above the south-southwest horizon at 7 p.m. For more information about the discovery, go to https://goo.gl/RTn92w.
Wednesday: You never see a giraffe on the ground in Ellensburg. But you can look for one every night in the sky. The constellation Camelopardalis the giraffe is circumpolar from Ellensburg’s latitude of 47 degrees north meaning it is always above the horizon. Don’t expect to be overwhelmed by the appearance of the stars in Camelopardalis. The brightest star in the constellation appears only about half as bright as the dimmest star in the Big Dipper. However, the actual luminosities of the three brightest stars in Camelopardalis are very high, each at least 3,000 times more luminous than the Sun. Alpha Camelopardalis, a mind boggling 600,000 times more luminous than the Sun, is seven fists above the northern horizon at 9 p.m.
Thursday: Do you see a hunter when you look at Orion? Betelgeuse and the bright star one fist to the right of it are the broad shoulders of the hunter. Rigel and Saiph, the bright star to the left of Rigel, represent the knees. The Maya saw the equilateral triangle formed by Rigel, Saiph, and the left-most belt star as the “Three Stones of the Hearth”. The Orion Nebula is in the center of the hearth and it represents the flame, called K’ak.
Friday: The whale’s tail is about two fists above the south-southwest horizon at 6 p.m. Deneb Kaitos, “whale’s tail” in Arabic, is one of the brightest x-ray sources within 100 light years of Earth. High x-ray activity typically indicates that a star recently moved off the main sequence and towards its death. But the chemical composition of Deneb Kaitos suggests it moved off the main sequence long ago. This shows that even our nearest celestial neighbors have a lot to teach us.
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 https://nightsky.jpl.nasa.gov/planner.cfm.