Thursday, July 24, 2025

The Ellensburg, WA sky for the week of July 26, 2025

Saturday: At 9:30 p.m., the bright star Regulus is to the lower right of the crescent moon, low on the west-northwestern horizon. Mars is nearby, one fist held upright and at arm’s length above the western horizon.

Sunday: Have you ever planned a vacation to a place because it was supposedly the up-and-coming locale? Then, when the vacation time finally arrives, you find out the place doesn’t live up to its billing. Over the past decade, astronomers strengthened earlier findings about the planetary system of the star Tau Ceti, one of our closest Sun-like star neighbors at 12 light years away. It has four planets classified as “super-Earths.” Two of the planets are on the edge of the habitable zone where the temperature is just right for having liquid water on their surface. Time for a va-ca-tion! Well, not so fast. Astronomers have only a lower limit to the planet masses so they may be too massive for complex life to form. And the Tau Ceti system has ten times as much mass in dust and rocks as our own solar system. So, you’ll want to do some research before you travel there. Tau Ceti is one and a half fists above the southeast horizon at 3:00 a.m. For more information about the system, go to https://skyandtelescope.org/astronomy-news/four-exoplanets-may-orbit-nearby-sun-like-star/.

Monday: Saturn is a half a fist above the eastern horizon at 11:30 p.m.

Tuesday: The Southern Delta Aquarid meteor shower peaks tonight, tomorrow night, and on into mid-August. Meteor showers are named after the constellation from which the meteors appear to originate. These meteors appear to come from a point in Aquarius near the star Delta Aquarii, also known as Skat. This point is about one and a half fists above the southeastern horizon at 1:00 am tonight. You can follow this point throughout the night, as it will remain a fist above Fomalhaut, the brightest star in that section of the sky. The Moon is in the waxing crescent to first quarter phase this week meaning it will not be up for many hours each night. For more information about this year’s shower, go to https://earthsky.org/?p=159138. As your mother might say, dress warmly and sit in a comfortable chair for maximum enjoyment. Meteors are tiny rocks that hit the Earth and burn up in the atmosphere.

Wednesday: At 4:30 a.m., Jupiter is one fist above the east-northeastern horizon and Venus is one and a half fists above the eastern horizon.

Thursday: Mizar is a well-known binary star in the constellation Ursa Major. You can find it at the bend in the Big Dipper handle, three fists above due northwest at midnight. Its name is Arabic for waistband. Mizar has an optical double called Alcor, which is less than a pinky width away and can easily be seen with the naked eye. Optical doubles are stars that are close together in the sky but do not orbit a common center of mass as true binary stars. Not wanting to deceive sky gazers who call Alcor and Mizar a binary star, two stars that DO orbit a common center of mass, Mizar actually is a binary. It was the first binary star system discovered using a telescope. Mizar A and Mizar B are about 400 astronomical units apart from each other and about 80 light years from Earth. 400 astronomical units is about 10 times the distance between the Sun and Pluto.

Friday: The Perseid meteor shower peaks in a week and a half. But there will be an increased number of meteors over the next two weeks. If the Moon is out when you want to look, position yourself so you are blocked from the Moon’s light. The meteors appear to come from a point just below the W of the constellation Cassiopeia. This point is about two and a half fists above the northeast horizon at 11:00 p.m. By dawn, this point is about seven fists above the northeast horizon. If you fall asleep or forget to set your alarm, you will be able to observe this shower from about 11:00 p.m. to dawn for the next two weeks in about the same location in the sky.

The Perseid shower is one of the longest lasting showers. For tips about optimizing your viewing this year, go to https://earthsky.org/?p=165416. These meteors are sand to pea-sized bits of rock that fell off Comet Swift-Tuttle. They travel about 40 miles per second as they collide with the Earth and burn up in the atmosphere.

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.

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