The Ellensburg, WA sky for the week of January 11, 2025

Saturday: 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 10:00 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 larger than the Sun.

Sunday: Tonight Mars is as close to Earth as it will be this orbital cycle. Find it in the southeastern sky at 10:00 p.m., about one fist to the lower left of the full moon. Jupiter is to the right of the moon, six fists above the south-southwestern horizon.

Monday: The very bright planet Venus is one and a half fists above the west-southwestern horizon at 7:00 p.m. Saturn is a half a fist to the upper left of Venus. Over the next few days, Venus will move up towards Saturn in the night sky.

Tuesday: Most constellations don’t look like the object their name refers to. That’s because most constellations don’t have such a simple object to emulate as Triangulum does. Triangulum is shaped like a… wait for it…. wait for it…. A thin isosceles triangle. Metallah is the only mononymous star in the constellation. In Latin this star is called Caput Trianguli, the head of the triangle. Triangulum is four and a half fists above due west at 10:00 p.m. The triangle is pointing straight down with Metallah. The Triangulum Galaxy can be seen with binoculars about half a fist to the lower right of Metallah. This is the galaxy that the USS Enterprise travels to after the warp drive engine malfunctions in The Next Generation episode called “Where No One Has Gone Before”.

Wednesday: 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. Hamal is just to the left of Triangulum and is the brightest star in that region of the sky.

Thursday: Mercury is just above the southeastern horizon at 7:15 a.m.

Friday: 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 due north at 9:00 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 https://nightsky.jpl.nasa.gov/planner.cfm. All times are Pacific Time unless noted.