The Ellensburg, WA sky for the week of June 18, 2022

Saturday: I hope that you have never been in a collision. It can be scary and dangerous. The biggest collision in our celestial neighborhood will occur in a few billion years when our Milky Way Galaxy will collide with the Andromeda Galaxy. Here’s an article about what it will look like: http://tiny.cc/19iytz If you can’t stay awake for a few billion years to see the collision, stay up until late at night to see the Andromeda Galaxy. First find the Great Square of Pegasus. At 4:00 a.m., the left hand corner of the square is about four and a half fists above the eastern horizon. Less than two fists to the left and down a little bit is another star the same brightness as the star at the corner of the square. From that star, hop about a half a fist up to a star that is about one fourth as bright. Less than another half fist in the same direction is a fuzzy oval patch of light known as the Andromeda Galaxy. The galaxy is impressive to see in binoculars. It consists of nearly a trillion stars and is 2.2 million light years away.

Sunday: Today is Father’s Day, the day to celebrate the person who gave you a father: your grandmother. In fact, celebrate this with your child by getting them the book “Woman in Science” by Rachel Ignotofsky (http://www.readwomeninscience.com/). This creatively drawn book highlights the contributions of 50 pioneers of science from Hypatia to Katherine Johnson, the main character in the recent movie “Hidden Figures”.

Monday: At 4:00 a.m., Jupiter is a half a fist to the upper left of the moon, low in the east-southeastern sky.

Tuesday: At 2:17 a.m. today, the Sun reaches its highest declination (the official name for sky latitude) of 23.5 degrees above the celestial equator. The celestial equator is the line that divides the northern sky from the southern sky. In Ellensburg, the Sun is about seven fists held upright and at arm’s length above the south horizon at 1:00 p.m. (noon standard time). Contrary to popular belief, the Sun is never straight overhead in Ellensburg or anywhere else in the 48 contiguous states. The northernmost portion of the world where the Sun can be directly overhead is 23.5 degrees north latitude. In ancient times, the Sun was in the constellation Cancer the crab on the first day of summer. Hence, 23.5 degrees north latitude has the nickname "Tropic of Cancer". Because the Earth wobbles like a spinning top, the Sun's apparent path through the sky changes slightly over time. Now, the Sun is in the constellation Taurus the bull on the first day of summer. However, citing the high cost of revising all the science books, geographers are not changing the name of 23.5 degrees north latitude to "Tropic of Taurus". The first day of summer is often called the summer solstice. However, astronomers refer to the summer solstice as the point in the sky in which the Sun is at its highest declination above the celestial equator. Summer starts when the Sun is at the summer solstice point.

Wednesday: At 4:00 a.m., Mars is a half a fist to the left of the moon, low in the east-southeastern sky.

Thursday: Venus is one fist above the east-northeastern horizon at 4:30 a.m. Mercury is to the lower left of Venus, about halfway to the horizon.

Friday: “Mom, I can’t sleep. It is too light out!” A poor excuse you say? Good astronomy skills, I say. The latest sunset of the year happens around this date. Surprisingly, the earliest sunrise and the latest sunset do not both happen on the longest day of the year, the day of the summer solstice. The earliest sunrise occurs just before the longest day and the latest sunset occurs just after the longest day. This phenomenon relates to the angle of the Sun’s path near rising and setting. In Ellensburg, that angle is about 66 degrees above the southern horizon at noon near the first day of summer. Because of the Earth’s orbit, which causes the Sun’s apparent motion, the angles are not symmetric. The asymmetries in orbital angles leads to the asymmetry in rise and set times. This year, the sun sets at about 9:01 p.m. between June 22 and June 29 as viewed from Ellensburg, WA. Find sunset data for your location at https://www.timeanddate.com/.

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.