Wednesday, January 7, 2015
The Ellensburg WA sky for the week of 1/10/15
Saturday: Do you have a dime? No, I’m not going to ask you to use a payphone. (“A what?” asked the young person.) Do you have a penny? No, I’m going to ask you to buy a gumball. (“Gum for a penny?” asked the young person.) But I will ask you to make a measurement at 5:15 p.m. Mercury and Venus are very close together a half a fist above the southwest horizon with Mercury being to the lower right of much brighter Venus. Hold a dime out at arm’s length. It should easily fit between them. Then hold a penny at arm’s length. Depending on the length of your arm, this may be a snug fit.
Sunday: How do you study the life cycle of a dog? Easy. Get a dog from the animal shelter, care for it for 15 years and study it. How do you study the life cycle of a star? Easy. Pick a star, watch it for a few billion years, and…. Wait a minute. Astronomers can’t observe something for a few billion years. Instead, they study stars that are at different points in their long life cycle and piece together the information from those different stars. What they do is like studying a one-year-old dog for a few minutes, then studying a different two-year-old dog for a few minutes, and so on. The sky in and near the constellation Orion provides an example of four objects at different points of star life.
First, find Rigel, the bright star in the lower right corner of the constellation Orion. This star, rapidly burning its fuel for a high energy but short-lived existence, is three and a half fists above the south horizon at 10 p.m. About one fist up and to the left are the three objects of Orion’s sword holder. The middle “star” is really a star-forming region called the Orion nebula. There you’ll find baby Suns. Now, look about two fists to the right and a little below Rigel. You should be looking at a star that is about one tenth as bright as Rigel but still the brightest in its local region. The third star to the right of that star is Epsilon Eridani, the most Sun-like close and bright star. Betelgeuse, in the upper left corner of Orion, is a star at the end of its life that started out life a bit larger than the Sun.
Monday: The snout of Taurus the Bull points to Comet Lovejoy for the next three nights. First, find the V-shaped grouping of stars, six fists above due south at 8 p.m. This is the Hyades cluster, representing the snout of Taurus. Comet Lovejoy is one fist to the lower right of the snout. The “V” will point right to it. On a clear night away from the city lights, you should be able to see the comet without optical aids. But in town, and to see detail, you’ll need binoculars. For more information about the comet and where to find it, go to http://goo.gl/imiDsi.
Tuesday: Orion stands tall in the southern sky. At 10:30 p.m., the middle of Orion’s belt is four fists above due south. And talk about belt tightening! Alnilam, the middle star in the belt, is losing mass at a rate of about 100 thousand trillion tons a day. That’s a 1 followed by 17 zeros tons per day.
Wednesday: Hit the road Mercury. And don’t you come back no more, no more. For a few weeks, Mercury has been hitting the road and moving away from the Sun in the sky. Today, Mercury is as far away from the Sun as it will get on the evening half of this cycle. This is known as its greatest eastern elongation. Yet, this distance does not translate into good viewing because Mercury will be very low in the sky. Mercury is a half a fist above the southwest horizon at 5:30 p.m. Over the next few weeks, Mercury will move toward the Sun in the sky. After it passes in front of the Sun, it will appear in the morning sky by mid February.
Thursday: January is the coldest month of the year so it is time to turn up the furnace. Fornax the furnace is one fist above due south at 7 p.m.
Friday: Saturn is about a pinky width to the right of the moon at 7 a.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 http://nightsky.jpl.nasa.gov/planner.cfm.