The Ellensburg, WA sky for the week of January 11, 2020

Saturday:   Last Saturday's planetarium show had some technical difficulties. So, we will be redoing the show today from noon to 1 p.m. CWU physics graduate and future science teacher Jessica Kisner will give a show about the winter sky. The nights are long and the sky is (sometimes) crisp and clear. So you ought to know what you are looking at. The show is free and open to all ages. There will be a show at noon on the first Saturday of every month of the school year hosted by different CWU astronomers and astronomy educators. The CWU Lydig Planetarium is room 101 in Science Phase II, just off the corner of 11th and Wildcat Way, H-11 on the campus map found at https://www.cwu.edu/facility/campus-map.

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 held upright and at arm’s length above due south at 10 p.m. It was not, is not, and never will be like our Sun. However, 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 one fist down from 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. Betelgeuse has been in the astronomy news lately because it has fallen from the 10th brightest star to the 21st brightest star in the night sky. Supergiant stars such as Betelgeuse are unstable and vary in size and shape over their years as a supergiant. These variations lead to variations in brightness. Astronomers think that a few different variation patterns that lead to slight changes in brightness individually are all happening at the same time, leading to a larger drop in brightness. For more information, go to https://www.skyandtelescope.com/observing/fainting-betelgeuse. 

Monday: When someone is angry, they may say “I’m seeing red.” For the next few days, people who  observe the morning sky will also see red. Mars and its rival Antares are neighbors in the sky for the next few days. Lest you think I am drumming up a fake rivalry, the prefix “ant” means “against”, “opposite”, or “rival”.  Ares is the Greek counterpart to the Roman god of war, Mars. So Antares literally means “rival to Mars”. At 7:00 a.m., Antares is one fist above the south-southeastern horizon and Mars is half a fist above it.

Tuesday: Venus is one and a half fists above the southwestern horizon at 6:00 p.m.

Wednesday: These next two weeks are the coldest 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.

Thursday: Have you ever looked down on the ground and spotted a penny? In Yakima? While you were standing in Ellensburg? If you have, then you may be able to see the star Hamal as more than just a point of light. It has an angular diameter that can be directly measured from Earth. Hamal, the brightest star in the constellation Aries the ram, has the same angular diameter as a penny 37 miles away. (For comparison, the moon is about half the diameter of a penny held at arm’s length.) Hamal is three fists above due west at 11:00 p.m.

Friday: Jupiter is finally starting to come out of the glare of the Sun in the morning sky. It is just above the southeastern horizon at 7:00 a.m. You’ll need a flat and clear horizon to see it.

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.