The Ellensburg, WA sky for the week of September 18, 2021

Saturday: Jupiter and Saturn are about two fists above the south-southeastern horizon at 9:00 p.m. Jupiter is the much brighter of the two. Saturn is about one and a half fists to the right of Jupiter, which is about one and a half fists to the upper right of the Moon. When you are looking at this part of the sky, you are looking in the direction of more than just the two planets. You are also looking in the direction of their moons. Titan, Saturn’s largest moon, is easily visible with a small telescope, about five “ring diameters” to the side of Saturn at this time. Jupiter’s four largest moons are also visible with a small telescope. Calisto and Ganymede are on one side of Jupiter, with Ganymede appearing the farthest away. Europa is visible in the other. If you have very clear skies, you may see Io on the Europa side, right next to Jupiter. Recently, a team of Canadian astronomers analyzed images of Jupiter from 2010 and estimated that Jupiter could have 600 moons at least 800 meters, a half mile, in diameter. They didn’t actually discover these moons. They just formulated a possible model of the Jovian system. For more on this, go to https://skyandtelescope.org/astronomy-news/jupiter-could-have-600-moons/. 

Sunday: The bright star Capella is two fists above due northeast at 11:00 p.m.

Monday: Shine on, shine on harvest moon, up in the sky. It’s just like a full moon in January, February, June and July. The only difference is that near the Autumnal Equinox (also known as the first day of fall), the full moon rises close to sunset resulting in a full night of light for the harvest. The harvest moon looks more orange than usual when it is near the horizon because of the dust kicked up from the harvest. The dust scatters the white light reflecting off the Moon resulting in slightly more of the red and orange components of the white light reaching your eyes. Although the Moon has a dull yellow color whenever it is near the horizon owing to light scattering off dust and atmospheric particles, the effect is more noticeable for the harvest Moon. For more information about the harvest moon, go to https://earthsky.org/astronomy-essentials/harvest-moon-2/. 

Tuesday: According to the “One world, group hug, love everyone” philosophy, political borders are human-made and can’t be seen from space so why can’t we all just get along. According to real world pragmatic discoveries, some human-made political borders CAN be seen from space. Since 2003, India has illuminated its border with Pakistan to prevent illegal crossings. In 2011, astronaut Ron Garan took a picture of that border from the International Space Station. For more information, including the photo, go to http://goo.gl/mY8xG.

Wednesday: At 12:22 p.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 6:50 a.m. and sets at 6:59 p.m. in the northern latitudes of the United States. At these latitudes, day and night are closest to equal duration on Saturday.

Thursday: Last year, 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 cellular life. But more recent studies show that the original scientists just found the signature of sulfur dioxide, a gas common on Venus. This recent phosphate news is an excellent example of science at work. In less than a year, 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”. 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 7:45 p.m. Venus is a half a fist above the southwestern horizon at this time.

Friday: The bright star Vega is about five fists above the western horizon at 11:00 p.m. Its fellow Summer Triangle star Deneb is about two fists above it. Altair, the third star in the triangle, is about four fists above the southwestern 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.

The Ellensburg, WA sky for the week of September 11, 2021

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 would say it poked an ape.” Sorry. Some stores have started sending out their Christmas catalogues 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 nearly four fists held upright and at arm’s length above the eastern horizon at 11:00 p.m.

Sunday: Fomalhaut, the southernmost bright star visible from the northern USA, is one fist above the south-southeastern horizon at 11 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. 

Monday: Venus and Mercury are just above the west-southwestern horizon at 7:30 p.m. Venus is bright and fairly easy to find. Mercury is more of a challenge. But tonight is your best chance for the next few weeks because it is at its greatest distance from the Sun in the sky this orbital cycle.  This orientation is called the greatest eastern elongation. Over the next few weeks, Mercury will move toward the Sun in the sky. By mid-October, it will be visible in the morning sky.

Tuesday: Neptune is in opposition tonight. Opposition means that Neptune is crabby. It means that it 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. Neptune is three fists above due southeast at 10:00 p.m. Tonight, it is midway between Jupiter and the Moon. You’ll need binoculars to see it. 

Wednesday: 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.

Thursday: Saturn is a half a fist above the Moon at 9:00 p.m. They are about two fists above the south-southestern horizon. Jupiter is about a fist and a half east of Saturn. The Moon moves about a half a fist eastward each night. That means tomorrow night the Moon will be about a half a fist below Jupiter at 9:00 p.m.

Friday: 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.

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.

The Ellensburg, WA sky for the week of September 4, 2021

Saturday: Jupiter is one and a half fists held upright and at arm’s length above due southeast at 9:00 p.m. Saturn is about two fists to the right of Jupiter.

Sunday: “Excuse me, do you have the time?”

“No, but the Big Dipper does.”

You can use the orientation of the Big Dipper to tell time with a precision of about 15-30 minutes. First, find the two stars at the far end of the Big Dipper cup, the stars that do not touch the handle. Draw an imaginary line segment starting at the North Star and passing through the two Big Dipper cup stars. Now, draw a big circle around the North Star. Your circle is a 24-hour clock. Number the circle from 0 hours at the top, counterclockwise to 12 hours at the bottom of the circle, and back up to 24 hours at the top. (O hours and 24 hours are the same on this clock because the day is 24 hours long.) The hour number on the big circle closest to where your imaginary line intersects this circle is called your raw time. Due to the location of the Big Dipper compared to the rest of the stars, the time nearest the intersection (the raw time) is correct for March 6. For any other night, subtract two times the number of months the current date is after March 6 from the raw time. For example, let’s say the imaginary line between the North Star and the Dipper stars is pointed to the right. That means the raw time is 18 hours or 6 p.m. If you made this observation tonight, which is six months after March 6, you would subtract two times six or 12 hours from the raw time.  Don’t forget to convert for daylight savings time if needed. For a more complete explanation on how to do the Big Dipper clock math, go to http://goo.gl/02HmA. If you prefer a more visual tool, and a fun project to do with your kids, there is a simple “star clock” template and instructions at https://skyandtelescope.org/observing/make-a-star-clock/. Use this paper star clock whenever your watch is broken. The Big Dipper is in the northwestern sky at 9:00 p.m. tonight.

Monday: Labor Day was the brainchild of labor unions and is dedicated to American workers. The first Labor Day was celebrated in 1882. The Greek mythical hero Hercules probably wished there was a Labor Day to commemorate his work. As punishment for killing his family while he was temporarily insane, he had to perform twelve nearly impossible tasks such as killing monsters or stealing things from deities. Hmmm. Maybe we shouldn’t commemorate his labors. But we can enjoy his constellation. The keystone asterism representing the body of Hercules is six fists held upright and at arm’s length above the western horizon at 10:00 p.m. For more information about the Labors of Hercules, go to http://goo.gl/ozVF5. 

Tuesday: School starts this week so it is time for a little geometry review. A square is a regular quadrilateral. This means it has four equal sides, four equal angles, and wears old fashioned clothing. Go outside at 10:00 p.m. tonight with a notebook in hand to sketch one. The Great Square of Pegasus is balancing on its corner three fists above the eastern horizon. The top corner of the square is two fists above the bottom corner. The other two corners are to the left and right of the line segment connecting the top and bottom corners. 

Wednesday: Venus is one and a half fists to the left of the waxing crescent Moon at 8:00 p.m. They are low in the south-southwestern sky.

Thursday: Geometry review, part 2. Go outside at 10:00 p.m. tonight with a notebook in hand. (Good teaching involves a little repetition.) A triangle is a polygon with three corners and three line segments as sides. A good example is the Summer Triangle made up of the bright stars Vega, Deneb and Altair. Altair is five fists above the southern horizon. Vega, the brightest star in the triangle, is seven fists above the western horizon. Deneb is a little bit east of straight overhead.  

Friday: The asteroid Pallas is at opposition tonight. That doesn’t mean that Pallas says “no” when you say “yes”. Opposition means that Pallas 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 an asteroid or planet. Pallas is three fists above the southeastern horizon at 10:00 p.m. First find bright Jupiter in the center of your binoculars’ field of view to the somewhat bright reddish star Hydor. Then, with Hydor at the center of your field of view, move your binoculars about one and a half fields of view to the upper left to reach Pallas. It is in the middle of a small parallelogram. As the days go by, Pallas moves to the lower right compared to the parallelogram.

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.