The Ellensburg, WA sky for the week of August 26, 2023

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 fists 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: June 26, 2018, July 9, 2019, July 21, 2020, August 1, 2021, and August 14, 2022. 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: Mars is just above the western horizon at 8:30 p.m. Over the next few weeks, Mars will move behind the Sun and into the morning sky. You don’t have to wait that long to see Jupiter.  It is about a fist and a half above the eastern horizon by midnight tonight.

Monday: You’ve seen all of the top 100 lists: top 100 ways to bench press, top 100 Uzbek astronomers, etc. Now get excited for this week’s full Moon by reading about and finding some of the lunar 100. Go to http://goo.gl/ldGvH6. This list describes 100 interesting landmarks on the Moon that are visible from Earth. They are listed from easiest to see, starting with the entire moon itself at number 1, to most difficult (Mare Marginis swirls, anyone?). Stay up all night to binge watch the moon or just make a few observations a month. It’s your decision. It’s our moon. Start your viewing tonight at 9:00 p.m. when the Moon is one fist above due southwest. I suggest starting with Mare Crisium, the circular, dark, basaltic plain in the upper right-hand portion of the moon. Items such as Crisium were named "Mare" by early astronomers who mistook them for seas, instead of the hardened lava beds that they really are. 

Tuesday: Need a caffeine pick-me-up? Make it a double. Need an astronomy pick-me-up? Make it a double double. Find Vega, in the constellation Lyra the lyre, nearly straight overhead at 9:00 tonight. Less than half a fist to the east (or left if you are facing south) of the bright bluish star 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.

Wednesday: “I’m a little teapot, short and stout. The galactic center, I pour it out.” (I’m a Little Teapot, astronomy version, 2023.) Despite its great size and importance, the center of our Milky Way galaxy and its giant black hole remains hidden to the naked eye behind thick clouds of gas and dust. By plotting the orbits of stars near the middle of the galaxy, astronomers have determined that the black hole’s mass is equal to about 4.5 million Suns. While you can’t see the actual galactic center, you can gaze in the direction of the center by looking just to the right of the teapot asterism in the constellation Sagittarius. This point is about one fist above the south-southwestern horizon at 9:00 p.m.

Thursday: Venus is nearly one fist above the eastern horizon at 5:30 a.m.

Friday: School starts soon. One of the most important lessons to learn in science class is to always save your data. Even if the data looks “wrong” or you don’t think it contains important information, you never know what future researchers might find in it. Two years ago, Kepler space telescope scientists reanalyzed older data and discovered an Earth-sized planet orbiting in the habitable zone of its host star. It turns out the previous computer algorithm misidentified it. Maybe there are other Earth-cousins hiding in the data somewhere. Read more about it at https://www.nasa.gov/press-release/earth-size-habitable-zone-planet-found-hidden-in-early-nasa-kepler-data.

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.