The Ellensburg, WA sky for the week of January 9, 2021

Saturday:  Winter is the best season for finding bright stars. And if you only want to set aside a few minutes, 10:00 p.m. tonight just might be the best time because the winter hexagon is due south. Starting at the bottom, find Sirius, the brightest star in the night sky, two and a half fists held upright and at arms length above the south horizon. Going clockwise, Procyon (6th brightest star visible from Washington state) is about two and a half fists to the upper left of Sirius. Pollux (12th brightest) is about two and a half fists above Procyon. Capella (4th brightest) is about two and a half fists to the upper right of Procyon and close to straight overhead. Going back to Sirius at the bottom, Rigel (5th brightest) about two and a half fists to the upper right of Sirius. Aldebaran (9th brightest) is about three fists above Rigel. Betelgeuse (7th brightest) is in the center of the hexagon. Adhara (16th brightest) is a little more than a fist below Sirius and Castor (17th brightest) is right above Pollux. That’s nine of the 17 brightest stars visible in the northern United States in one part of the sky. If it is too cloudy, stay indoors and watch this tour, found at https://skyandtelescope.org/astronomy-news/tour-15-of-the-brightest-stars-on-new-years-eve-video/

Sunday: At 5:00 p.m. Mercury, Jupiter, and Saturn are all within about two degrees of each other just above the southwestern horizon. They’ll remain close together in the sky for the next few days as Jupiter and Saturn move towards the Sun while Mercury moves away.

Monday: At 7:00 a.m., Venus is about a thumb-width to the left of the waning crescent Moon. They are just above the southeastern horizon.

Tuesday: 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.

Wednesday: You think wintertime weather is bad in Ellensburg. Astronomers have discovered storms and earth-sized clouds on a brown dwarf. These are cool, small stars that are not massive enough to fuse hydrogen atoms and fuse hydrogen. In fact, they are more similar to gas giant planets such as Jupiter than to the Sun. Luckily, astronomers are getting better at predicting this weather. That means you can plan your brown dwarf picnic and it can be more enjoyable. For more information, go to https://www.nasa.gov/feature/jpl/scientists-improve-brown-dwarf-weather-forecasts 

Thursday: 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.

Friday: Mars is five and a half fists above due south at 6:30 p.m. Uranus is about a thumb-width to the left of it. You’ll need binoculars to see Uranus. With Mars at the right hand edge of your field of view, Uranus will be near the center. Follow the two planets over the next few night. They will be moving closer together in the sky.

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.