Friday, April 23, 2021

The Ellensburg, WA sky for the week of April 24, 2021

Saturday: As the rock group Journey once thought of singing, “Wheel in the sky keeps on turnin’. I know where the Dipper’ll be tomorrow.” Every night, the Big Dipper and Cassiopeia make a wheel in the sky that turns around the North Star in a counter clockwise direction. Every year on April 24 at 10:00 p.m., the Big Dipper is straight overhead and W-shaped Cassiopeia is low on the northern horizon. Every year on April 25 at 10:00 p.m., the Big Dipper is straight overhead and W-shaped Cassiopeia is low on the northern horizon. Every year on April 26 at 10:00 p.m., the Big Dipper is straight overhead and W-shaped Cassiopeia is low on the northern horizon. Oh, am I boring you? Of course, there are subtle charges in the position from night to night. Each northern constellation moves about one degree counterclockwise from one night to the next. But this is not going to change their position in the sky drastically over a few days. So, if you know where the Big Dipper is tonight, you DO know where it’ll be tomorrow. If you are really struggling to understand this concept, Don’t Stop Believin’ in yourself. Just keep studying Faithfully. 

Sunday: Orion stands low in the southwestern sky. At 9:00 p.m., the middle of Orion’s belt is one and a half fists held upright and at arm’s length above the west-southwest horizon. And talk about belt tightening! Alnilam, the middle star in the belt, is losing mass at a rate of about 100 thousand trillion tons a day. That’s a 1 followed by 17 zeros tons per day.


Monday: Venus and Mercury are just above the west-northwest horizon at 8:30 p.m. These objects are two of our closest celestial neighbors. One hundred years ago tonight, the astronomers Heber Curtis and Harlow Shapley were debating the distances of some of our farthest neighbors: galaxies. Curtis argued that the universe consisted of many galaxies millions of light years away. Shapley thought that the spiral structures seen in telescopes were actually a part of the Milky Way. They also had different views on the size of the Milky Way. Learn more about their debate, called the Great Debate, at https://stardate.org/radio/program/2020-04-24. Learn more about the Milky Way by watching the center of it rise over the southeastern horizon at about 1:00 a.m.


Tuesday: Some open star clusters are easy to find and see, such as The Pleiades and The Hyades clusters in the constellation Taurus the bull. Some are difficult to see. M35, an open star cluster in the constellation Gemini the Twins, is in the middle. It doesn’t jump out at you but it is easy to find if you have help. Mars helps you tonight. M35 is about a pinky thickness below Mars, three fists above the western horizon at 9:30 p.m. It is a family of a few thousand stars about 3,000 light years away. Open star clusters are young, this one being about 100 million years old.  The cluster is best seen using binoculars or a small telescope.


Wednesday: Bright Jupiter is a little more than one fist above the southeast horizon at 5:30 a.m. Saturn is a fist to the upper right of Jupiter.


Thursday: The bright star Antares is a half a fist below the Moon, low in the southwestern sky at 5:30 a.m. It will be a challenge to find it in the morning twilight.


Friday: CWU encourages physical distancing. But astronomy learning lives on! The Physics Department and STEM Teaching Program is hosting a First Saturday VIRTUAL planetarium show tomorrow from noon to 1:00 p.m. CWU STEM Teaching planetarium interns Grace Warren and Kendra Gardner will be presenting their project called Kepler Space Program: Mission to Mars, a multi-media astronomy lesson. In addition, they will also present a mission-simulation curriculum that Kendra and others developed last summer. Finally, CWU physics professor Bruce Palmquist will give a general overview of Mars and the May sky. There is a virtual planetarium show on the first Saturday of nearly every month of the school year. Register at http://tiny.cc/oohwtz


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.

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