The Ellensburg, WA sky for the week of May 30, 2026

Saturday: Two of the best, and certainly the most available, tools for viewing the night sky are your eyes. Your eyes let you see the entire sky in just a few seconds. Your eyes can read star charts, decipher astronomy apps, and spot meteors while your friend is still setting up her tripod. Your naked eyes are not as effective as gathering light. They work well when the light source is comparatively bright and the detailed features are fairly large. It’s best to practice on a special Solar System body known scientifically as the Magnificent Optical Object of Nearness. Artists such as Jan van Eyck and Leonardo da Vinci produced the first realistic naked eye depictions of the Magnificent Optical Object of Nearness. I challenge you to use your unaided eyes to observe craters on the Magnificent Optical Object of Nearness, better known as the Moon. For a guide to the most prominent craters, go to http://goo.gl/JLhraO.

Tonight’s and tomorrow night’s moon is the second full moon of the month, which is called a blue moon. That name originates from a mistranslation of a story from the 1500s.

Sunday: You know Metis and Thebe and Adrastea and Amalthea. Io and Ganymede and Callisto and Europa. But do you recall? There are 97 Jovian moons in all. Just 60 years ago, Jupiter was thought to have only 12 moons. But astronomers are red nosed with delight that the advent of supersensitive electronic cameras has caused the number of discovered moons to rapidly increase. Jupiter’s 115 moons range in size from Ganymede, the largest in the Solar System with a diameter of 5,262 kilometers, to numerous moons with diameters of only one kilometer. In the past few years, Saturn moved to first place in the moon race with 292 moons. Uranus follows Jupiter with 29. Then comes Neptune with 16, Mars with 2, and Earth with 1. Our moon is the fifth largest in the Solar System, with a diameter of 3,475 kilometers. (One kilometer is 0.62 miles.) Even dwarf planets have moons. Pluto has 5 while both Haumea and Quaoar have 2. Eris, Makemake, Orcus, and Gonggong have 1 each. Eris is an outer solar system object that was discovered in 2005 and named in September of 2006. Because astronomers thought it was larger than Pluto, people called it the tenth planet for a while. (More recent measurements show Eris to be a little smaller in diameter than Pluto.) Haumea, the newest dwarf planet with a moon, was discovered in 2004 and officially named a dwarf planet on September 17, 2008. Go to https://solarsystem.nasa.gov/moons/ for more information about Solar System moons. You’ll have to wait until tonight to see our moon and to see some of the other Solar System planets that have moons.

Monday: Jupiter, Venus, and Mercury and all low in the west-northwestern horizon at 9:45 p.m. Jupiter is nearly two fists above the horizon, to the upper left. Venus, the brightest of the three, is in the middle. Mercury, on the lower right, is about half a fist above the horizon.

Tuesday: Summer is nearly here. How do I know? Because the days are very long. Because the temperature is rising. Because the school year is ending. Also, because the Summer Triangle is fairly high in the eastern sky at 11:30 p.m. Vega, the third brightest star visible from Ellensburg, is about five fists above the eastern horizon. Deneb, at the tail of Cygnus the swan, is about three and a half fists above the east-northeast horizon. The third star in the triangle, Altair in Aquila the eagle, is nearly two fists above the eastern horizon.

If you want to put somebody off, tell them to wait until Deneb sets. At Ellensburg’s latitude of 47 degrees, Deneb is a circumpolar star meaning it never goes below the horizon.

Wednesday: At 4:15 a.m., Mars is half a fist above the east-northeastern horizon and Saturn is one and a half fists above the east-southeastern horizon.

Thursday: Antares is one and a half fists above the south-southeastern horizon at 11:45 p.m.

Friday: The bright star Capella is a half a fist above the north-northwestern horizon at 11:30 p.m. Interestingly enough, even though it is in the northern sky, it is only about two fists from the Sun. If you viewed Capella from Ketchikan, the southernmost city in Alaska, Capella would be one and a half fists above the horizon. The Sun would be a half a fist below the horizon, close enough to the horizon that there would be a constant twilight glow.

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.