The Ellensburg, WA sky for the week of September 28, 2024

Saturday: You learned about Cassiopeia last week. The astronomer Caroline Herschel discovered an open star cluster that looks like a rose over 200 years ago. 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.

Sunday: Saturn is two and a half fists above the southeastern horizon at 9:00 p.m.

Monday: 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.

Tuesday: Jupiter is one fist above the east-northeastern horizon at 11:00 p.m. By 1:00 a.m., Jupiter is three fists above due east and Mars is where Jupiter used to be, one fist above the east-northeastern horizon.

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, nearly six 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: Four years ago, astronomers announced that they detected phosphine, a possible biosignature of life, in the upper atmosphere of Venus. Although the surface of Venus is inhospitable, astronomers have long speculated that the upper atmosphere could harbor life. Not Cloud City life from The Empire Strikes Back but maybe microbial life. Last year, astronomers concluded that the original scientists found the signature of sulfur dioxide, not life. Last year, the private company Rocket Lab published details about the first privately funded mission to another planet - their trip to Venus. The trip was originally scheduled to launch this year but has been delayed to at least 2025. This Venus storyline is an excellent example of science at work. In less than two years, science went from “we may have found a marker for life on Venus” to “it is unclear if we found a marker for life” to “we probably didn’t find a marker for life” to “let’s visit Venus to closely study the thing we thought was a marker for life”. Do an internet search of the words Venus and phosphine and read the articles to follow the story. To get yourself in the mood, go outside at 7:15 p.m. Venus is a half fist above the west-southwestern horizon at this time. Read more about the potential mission at https://www.space.com/rocket-lab-private-venus-mission-delayed-2025.

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 21, 2024

Saturday: At 5:30 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 takes 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 6:48 a.m. and sets at 7:00 p.m. in the northern latitudes of the United States. At these latitudes, day and night are closest to equal duration on Tuesday.

Sunday: “There’s water in them thar craters,” frozen water, that 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 one fist above the north-northeast horizon at 11:00 p.m.

Monday: To the people of Ancient Greece, the stars that are about five and a half fists above the northeastern and eastern horizons, respectively, at 10:00 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.

Tuesday: 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 in 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.

Wednesday: Mars is less than a half a fist to the lower right of the last quarter moon at 6:00 a.m. Jupiter is to the upper right of the moon.

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: Saturn is exactly two and a half fists above due southeast at 9:00 p.m.

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 7, 2024

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 on nearly the same date every year: July 9, 2019, July 21, 2020, August 1, 2021, August 14, 2022, and August 26, 2023. 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.

Sunday: “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 would 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 and four fists above the eastern horizon at 11:30 p.m.

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: 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 that is 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.

Wednesday: At 1:00 a.m., Jupiter, the brightest point of light in the sky at this time, is one and a half fists above the east-northeastern horizon. Mars is a fist to the lower left of Jupiter.

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://goo.gl/cL5t9p.

Friday: Arcturus is two fists above the western horizon at 9:00 p.m.

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.