The Ellensburg, WA sky for the week of August 17, 2024

Saturday: “The sky is black (or light polluted), the stars are white (or red or orange or yellow or blue), the whole world gazes upon the sight (except where there are too many city lights or people are lazy.” Wow. It is difficult to write a flowing set of lyrics when there are so many parenthetical thoughts. Most people think of the sky’s blackness as a lack of stars. But dark patches in the Milky Way are actually massive clouds of dust that are blocking the stars behind them. Two of the most prominent are dark nebulae B142 and B143 in the constellation Aquila the eagle. These are easy to find and enjoy with binoculars. First find the bright white star Altair, five fists held upright and at arm’s length above due south at 11:00 p.m. Then move your binoculars up and to the right a little bit to the next bright star Tarazed, about one fifth as bright. B142 and B143 are to the upper right of Tarazed. They make an “E” shape in the sky; fitting because American astronomer E. E. Barnard first proposed that these were dust clouds and not simply big spaces between the stars. For more information about dark nebulae, including many more to look at with binoculars, go to https://goo.gl/9tiqdh.

Sunday: Arcturus is two and a half fists above due west at 10:15 p.m. This star, whose name means bear watcher, is the brightest in the sky’s northern hemisphere. It follows Ursa Major, the Great Bear, around the North Star. Arcturus is the closest giant star to Earth. It is one of the few stars whose diameter can be measured directly rather than being inferred from its density and mass, which themselves are derived from other parameters.

Monday: The August full moon is traditionally called the full sturgeon moon by Midwest and northeastern Native American tribes because the lake sturgeon in this part of the country were easiest to catch during this full moon time. This month’s full moon is a supermoon, meaning it occurs close to perigee and appears large in the sky. Read all about Supermoon-mania at https://earthsky.org/human-world/what-is-a-supermoon.

Tuesday: Saturn is about a thumb width to the upper right of the moon at 10:00 p.m. They are one fist above the east-southeastern horizon.

Wednesday: All stars rotate. Our Sun takes a little less than one Earth month to rotate once on its axis. Astronomers studied the relationship between mass, stellar rotation, and planetary formation by aiming NASA’s recently retired Kepler space telescope toward the Pleiades open star cluster. All 1,000 stars in this group are nearly the same age, 125 million years old. Since all of the stars are the same age and formed from the same set of materials, astronomers have the ideal “laboratory” to isolate the role star mass plays on star rotation and evolution. Read more about the findings at https://www.jpl.nasa.gov/news/kepler-watches-stellar-dancers-in-the-pleiades-cluster. See the Pleiades for yourself, about a half a fist above the east-northeastern horizon at 11:30 p.m.

Thursday: Seventeenth century astronomers documented the appearance of a new star, or “nova”, in 1670. However, as modern astronomers studied the records of the star, called Nova Vulpeculae 1670, they realized it didn’t have the characteristics of a typical nova because it didn’t repeatedly brighten and dim. It brightened twice and disappeared for good. Turning their telescopes to the region, they discovered the chemical signature to be characteristic of a very rare collision of two stars. For more information about this discovery, go to http://goo.gl/rJnC2G. Nova Vulpeculae 1670 is right below the binary star system Alberio, the head of Cygnus the swan. Alberio is five fists above due south at 11:00 p.m.

Friday: The bright planet Jupiter is five fists above the east-southeastern horizon at 5:30 a.m. Mars is about a half a fist to the lower left of Jupiter.

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.