The Ellensburg WA sky for the week of 6/15/19

Today:  Tomorrow is Father’s Day, the day to celebrate the person who made you a father. No, not her. You celebrated her last month. (You didn’t forget, did you?!) Celebrate your child by getting her/him 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”.

Sunday: You’ve seen all of the top 100 lists: top 100 ways to use Super Glue, top 100 Thai restaurants in Ellensburg, etc. Now get excited for this week’s full Moon by reading about and finding some of the lunar 100 at 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 10:00 p.m. when the Moon is one and a half fists held upright and at arm’s length above the southeast horizon. 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. If you are wondering about that bright point of light about a half a fist to the right of the Moon, it’s Jupiter.

Monday: Summer is nearly here. How do I know? Because the days are very long. Because the temperature is rising. Because kids are getting out of school. Also, because the Summer Triangle is fairly high in the eastern sky at 11 p.m. Vega, the third brightest star visible from Ellensburg, is about six fists above the east horizon. Deneb, at the tail of Cygnus the swan is about four fists above the east-northeast horizon. The third star in the triangle, Altair in Aquila the eagle, is two and a half fists above the east horizon.

If you want to put somebody off, tell her to wait until Deneb sets. At Ellensburg’s latitude of 47 degrees, Deneb is a circumpolar star meaning it never goes below the horizon.

Tuesday: Saturn is less than a half a fist above the Moon at 11 p.m. They are both just barely above the southeast horizon.

Wednesday: Mercury and Mars are right next to each other in the evening twilight sky this week. Mercury is about four times brighter than Mars. They are about a fist above the west-northwest horizon at 9:30.

Thursday: 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: https://www.universetoday.com/141750/this-is-what-itll-look-like-when-the-milky-way-and-andromeda-galaxies-collide-billions-of-years-from-now/. If you can’t stay up 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 2:30 a.m., the left hand corner of the square is about three fists above the east-northeast 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.

Friday: Early this morning, the summer solstice occurs. This is when 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 of 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 point above the celestial equator. Thus, summer starts when the Sun is at the summer solstice point. This year, that happens at 7:56 a.m. Pacific Daylight Time.

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.