The Ellensburg, WA sky for the week of May 16, 2020

Saturday:  Every year near the summer solstice, the orbital path of the International Space Station (ISS) is aligned with the Earth’s day-night terminator line, meaning the ISS is illuminated by the Sun for its entire orbit. Since the ISS just takes about 90 minutes to orbit the Earth, it will be visible about five times a night from many locations. For more information about the ISS’s orbit and when to see it, go to https://www.skyandtelescope.com/observing/watch-international-space-station/. You can see the ISS tonight in central Washington state rising in the western sky at 9:46 pm, 11:22 pm, 1:00 am, 2:37 am, and 4:14 am.

Before your long night of ISS observations, look to the northwest right after sunset. Mercury has made its way into the evening sky. It is less than one fist above the west-northwestern horizon at 9:00 p.m., about halfway between the horizon and the much brighter Venus.

Sunday: Did you get up early to spot the ISS? At 4:30 a.m., just after the last ISS pass of the night, look two fists above the south-southeastern horizon. Bright Saturn is less than a half a fist to the left of the very bright Jupiter.

Monday:  Are you thirsty? I'll wait while you get some water. I will NOT wait while Corvus the crow gets you some water. The Greco-Roman god Apollo made this mistake. He sent Corvus the crow to get some water in the cup known as Crater. Some figs distracted Corvus and he waited for them to ripen so he could eat them. When Corvus got back late, Apollo put Corvus and Crater in the sky with the gently tipping cup just out of the reach of the perpetually thirsty crow. Corvus is a trapezoid-shaped constellation about two fists held upright and at arm’s length above due south at 9:30 p.m. Crater is just to the right of Corvus.

Tuesday: You can set your watch tonight by carefully observing Navi, the center star in the W-shaped Cassiopeia. It will be due north at exactly 10:06 p.m. However, another star in Cassiopeia is causing astronomers to doubt whether or not they can use neutron stars as the most precise known clocks in the universe. Neutron stars have such a precise spin rate that they are used to set clocks on Earth. However, in 2013, astronomers using NASA’s Swift x-ray telescope noticed that the neutron star called 1E 2259+586 exhibited a spin glitch that had never been seen before. The spin rate of about eight times a minute decreased by 2.2 millionths of a second. Read more about this at http://goo.gl/C4V8R1. In 2016, astronomers using NASA’s Swift x-ray telescope observed the slowest rotating neutron star, once every 6.5 hours. What is it with using a telescope named Swift to make discoveries about something slowing? Maybe that slow developing question will be answered at https://tinyurl.com/y6ag6g7c.  

Wednesday: Are you thirsty when you get up in the morning? I know you are not waiting for Corvus. That’s okay because the Big Dipper is positioned to hold water in the morning sky. Look three fists above the northwest horizon at 4:30 a.m. You’ll see three stars that make a bent handle and four stars that make a cup.

Thursday: Mercury is about a pinky-width below Venus low in the west-northwestern sky at 9:15 p.m.

Friday: Are you up at 1:59 a.m., looking due north and thinking you see a UFO coming to take you away? That's no UFO. It's the bright star Capella, a circumpolar star that never goes below the horizon as viewed from Ellensburg. 

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.