The Ellensburg, WA sky for the week of September 27, 2025

Saturday: Mars is right above the west-southwestern horizon at 7:30 p.m. Antares, which means “rival of Mars", is less than a half a fist to the right of the moon, low in the south-southwestern sky.

Sunday: You learned about Cassiopeia last week. Over 200 years ago, the astronomer Caroline Herschel discovered an open star cluster that looks like a rose. This cluster, called Caroline’s Rose, is about 6,500 light years away and consists of about 1,000 stars that are one third the age of the Sun. Through binoculars, it looks like a fuzzy patch. At 10:00 p.m., find the star at the top of the sideways “W” known as Cassiopeia. It is six fists held upright and at arm’s length above due northeast. When that star is in the lower left portion of your field of view, Caroline’s Rose is in the center to upper right. For more information about Caroline’s Rose, go to https://stardate.org/radio/program/2020-09-09.

Monday: Saturn is three fists above due southeast at 10:00 p.m.

Tuesday: Since Halloween is a month away, the stores are filled with bags of candy clusters. Use this reminder to take time to look at a star cluster. The Hyades cluster is an open star cluster that represents the V-shaped face of Taurus the bull. It is one of the biggest and nearest star clusters with about 200 stars 150 light years away. The Hyades cluster was the first cluster to be the subject of detailed motion studies. These studies allowed astronomers to pinpoint the distance to the Hyades and provide important information about the scale of the universe. Aldebaran, about one fist above the east-northeastern horizon at 11:00 p.m., is a foreground star and not a part of the Hyades cluster.

Wednesday: Need a caffeine pick-me-up? Make it a double. Need an astronomy pick-me-up? Make it a double double. Find the bright bluish star Vega, in the constellation Lyra the lyre, five and a half fists above due west at 10:00 p.m. Less than half a fist above Vega is the “star” Epsilon Lyra. If you look at Epsilon Lyra through binoculars, it looks like two stars. If you look at Epsilon Lyra through a large enough telescope, you will notice that each star in the pair is itself a pair of stars. Each star in the double is double. Hence, Epsilon Lyra is known as the double double. The stars in each pair orbit a point approximately in the center of each respective pair. The pairs themselves orbit a point between the two pairs.

Thursday: At 6:00 a.m., Venus is one fist above due east and Jupiter is five and a half fists above the southeastern horizon.

Friday: In 1987, the rock group Def Leppard sang “Pour some sugar on me, in the name of love. Pour some sugar on me, come on, fire me up”. In 2012, some European astronomers “found some sugar near stars, they were very young. Found some sugar near stars, out where planets formed.” Astronomers observed molecules of glycolaldehyde, a simple form of sugar, in the disk of gas and dust orbiting young binary stars. This is the first time astronomers have found this simple sugar so close to a star indicating that organic molecules can be found in planet-forming regions of stars. For more information, go to http://goo.gl/tfwy1.

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.

The Ellensburg, WA sky for the week of September 20, 2025

Saturday: Saturn is in opposition tonight. That doesn’t mean that Saturn is stubborn. Opposition means that Saturn is on the opposite side of the Earth as the Sun. When an object is in opposition, it is at its highest point in the sky during the darkest time of the day. Thus, opposition is typically the best time to observe a planet. Saturn is about three and a half fists held upright and at arm’s length above due south at 1:00 a.m. It is nearly two fists above due southeast at 10:00 p.m. Careful readers of this column may recall that Saturn is in opposition about 12 days later each year: July 21, 2020, August 1, 2021, August 14, 2022, August 26, 2023, and September 7, 2024. An outer planet is in opposition when Earth passes it up as both orbit the Sun. The farther out a planet is, the less it has moved along its orbit, and the closer it is to exactly one year from one Earth passing to the next. For comparison, it is about 18 months between successive oppositions for Mars. Saturn is three fists above due southeast at 10:30 p.m. tonight.

Sunday: Tonight’s moon phase is new. Typically, that is pretty boring. Tonight, in the South Pacific and New Zealand it will be pretty exciting because there will be a partial solar eclipse visible from there. For more information so share with your New Zealand friends, go to https://www.timeanddate.com/eclipse/solar/2025-september-21

Monday: At 10:30 a.m. PDT, the center of the Sun crosses the celestial equator and passes into the southern sky. The celestial equator is an imaginary line that divides the sky into a northern and southern half. When the Sun is in the southern half of the sky, it appears to take a shorter path from rising to setting. It also does not get as high in the sky at noon. This leads to shorter days and longer nights. Since the Sun crosses the celestial equator today, there is an instant when it is equally in the northern and southern sky, called the north and south celestial hemispheres. This so-called “equal night” is given by the Latin word equinox. Thus, today is known as the Autumnal Equinox. However, the day and night are not of equal duration today. The sun rises at 6:49 a.m. and sets at 6:58 p.m. in the northern latitudes of the United States.

Tuesday: Mars is right above the west-southwestern horizon at 7:30 p.m.

Wednesday: To the people of Ancient Greece, the stars that are about five and a half fists above the northeastern and eastern horizons, respectively, at 10:30 p.m. were known as Cassiopeia and Andromeda, a mythological queen and her daughter. But not all cultures imagined the same pictures in the sky. To the people of Polynesia, the stars of Cassiopeia and Andromeda represented a dolphin, called Kwu. Cassiopeia formed its tail, the brightest stars of Andromeda formed its fins, and its fainter stars outlined the dolphin’s body.

Thursday: Ask someone which day in September has the same duration day and night. Go ahead, ask someone. Why are you still reading this? I can wait. If that person says the first day of autumn, they are wrong. Today, three days after the first day of autumn, is the date on which day and night are closest in duration. There are two main reasons for this. First, the atmosphere acts like a lens, bending light from the Sun above the horizon when the Sun is actually below the horizon. This makes the Sun appear to rise before it actually rises and appear to set after it actually sets. Second, fall starts when the center of the Sun passes through the point called the autumnal equinox. But the Sun is not a point. The upper edge of the Sun rises about a minute before the center of the Sun and the lower edge sets a minute after the center of the Sun. Thus, even if we didn’t have an atmosphere that bends the sunlight, daytime on the first day of autumn would still be longer than 12 hours.

Friday: At 6:00 a.m., Venus is a little more than a fist above due east. At this time, Jupiter is five fists above the southeastern horizon.

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.

The Ellensburg, WA sky for the week of September 13, 2025

Saturday: Mars and Spica are just above the west-southwestern horizon at 8:00 p.m.

Sunday: While many people think they need a telescope to enjoy looking at the night sky, some objects actually look better through binoculars. Open star clusters are one of those types of objects. M39, the 39th object in Charles Messier’s catalog, is straight overhead at 11:00 p.m. This open star cluster contains about 30 stars in a region about seven light years across and a thousand light years away. A quick trigonometry calculation shows that the cluster is about the same size as the full moon in the night sky. Read more about M39 at https://stardate.org/radio/program/2022-09-04.

Monday: Saturn is one and a half fists above the east-southeastern horizon at 9:00 p.m.

Tuesday: “There’s water in them thar craters,” frozen water, which is. There has been speculation since the 1960s and indirect evidence since the 2000s of water on the Moon. Three years ago, astronomers studied data from four earlier missions. They noticed that the light reflecting off the bottom of craters near the lunar South Pole showed characteristics of light reflecting off pure ice. The water likely came from comet impacts or other solar system objects with trace amounts of water ice. Last summer, the Indian Space Research Organization became the fourth country to successfully land on the moon when Chandrayaan-3 landed near the lunar South Pole to study the water there. Read more about it at https://www.space.com/chandrayaan-3-moon-south-pole-why-nasa-wants-to-go-too. The moon is five fists above the eastern horizon at 6:00 a.m. Jupiter is less than a half fist to the lower right of the moon.

This will be a good day to try to see a planet during the day. Wait until the sun rises. Next, find the moon with your naked eye. Then aim your binoculars at the moon. Look for Jupiter below the moon. Finally, move away the binoculars and look at that same spot with your naked eye.

Wednesday: Fomalhaut, the farthest south of all the bright stars visible in the northern United States, is one fist above the south-southeastern horizon at 10:30 p.m.

Thursday:  Mnemonics are helpful for remembering astronomy facts. (Similarly, “Johnny Mnemonic,” the 1995 cyberpunk film, was helpful in getting Keanu Reeves’ career going.) After all, school children around the world are learning the order of the planets by remembering, “My very excellent mother just served us nine….” Oops, I guess that one needs updating with Pluto being classified as a dwarf planet. Well, here’s one that will not need updating for tens of thousands of years: the order of the stars in the Big Dipper. Because the nighttime stars are so far away from us, their actual motion through the sky, called their “proper motion” is not noticeable over even thousands of years. That is why the constellations have remained the same since ancient times. But two stars in the Big Dipper have a proper motion large enough such that in 100,000 years; the stars will no longer make a dipper shape. You can see this simulation at the American Museum of Natural History video found at https://youtu.be/sBfUBtdo8yo. Until then, you can remember the names of the seven dipper stars in order from handle to cup by remembering this helpful advice for teens: “AM, ask mom. PM, dad.” The stars are Alkaid, Mizar, Alioth, Megrez, Phad, Merek, and Duhbe. The Big Dipper is one fist above the northern horizon at midnight.

Friday: The moon, Venus, and the star Regulus form a tight cluster one and a half fists above due east at 6:00 a.m. Venus is about 100 times the brightness of Regulus. Both are to the upper right of the moon.

Today is an even better day to see a planet during the day. Wait until the sun rises. Next, find the moon with your naked eye. Then aim your binoculars at the moon. Look for Venus above the moon. Finally, move away the binoculars and look at that same spot with your naked eye.

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.

The Ellensburg, WA sky for the week of September 6, 2025

Saturday: “You know Aries and Cancer and Draco and Libra. Leo and Pisces and Virgo and Hydra. But do you recall, the pointiest asterism of all? Triangulum, the three-sided asterism, had a very pointy shape. And if you didn’t know it, you could say it poked an ape.” Sorry. Some stores have started sending out their Christmas catalogs and that has put me in the mood to modify some Christmas songs. Anyway, Triangulum is a small constellation between the more prominent Andromeda and Aries. Its main feature is a skinny triangle oriented parallel to the ground and two and a half fists held upright and at arm’s length above the east-northeastern horizon at 10:00 p.m.

Sunday: The September full moon goes by many names. The Western Abenaki call it the Corn Maker Moon because of the impending harvest. The Tlingit call it the Child Moon because this is the time of year many animals wean their young. The Ojibwe call it the Falling Leaves Moon because the trees are starting to lose their leaves. This month, everyone in the Eastern Hemisphere will call it the Red Moon because there will be a total lunar eclipse visible throughout that hemisphere. During a total lunar eclipse, the Earth’s atmosphere acts like a prism and spreads the Sun’s white light into its component colors, with the red light hitting the moon. If you have friends in the Eastern Hemisphere, send them the link https://www.timeanddate.com/eclipse/lunar/2025-september-7 for more information.

For more about full moon names, go to https://www.almanac.com/full-moon-names.

Monday: Fomalhaut, the southernmost bright star visible from the northern USA, is one fist above the south-southeastern horizon at 11:00 p.m. In 2008, Fomalhaut and its surroundings became the first star system with an extrasolar planet to be directly imaged. See the family photo at https://apod.nasa.gov/apod/ap081114.html.

Tuesday: Saturn is one fist above the east-southeastern horizon at 9:00 p.m.

Wednesday: Mars and the bright star Spica are less than a half a fist above the west-southwestern horizon at 8:00 pm. Reddish mars is to the upper right of the brighter Spica.

Thursday: Earlier this week, you read about Fomalhaut, the second brightest star with a planet. The brightest star known to have a planet is Pollux, in the constellation Gemini. (First vs. second brightest is meaningless here because they are nearly identical in magnitude, 1.15 vs. 1.16.) Pollux is four and a half fists above due east at 5:30 a.m., right below its “twin” star Castor. Read more about Pollux at https://skyandtelescope.org/astronomy-news/meet-pollux-red-giant-exoplanet/.

Friday: Venus is two fists above due east at 6:00 a.m. Jupiter is four and a half fists above the east-southeastern horizon, to the lower right of Pollux and Castor.

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.