The Ellensburg WA sky for the week of 6/17/17

Saturday: 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: Two years ago astronomers using a radio telescope in Australia discovered the source of fleeting radio signal bursts that had been a mystery for 17 years. And they didn’t have to probe the depths of deep space. They only had to probe the depths of… the observatory kitchen. It turns out the signal came from opening the microwave door prematurely. Read more about The Microwave Emission here: http://goo.gl/Ftb04C. Sheldon Cooper used similar methods of science when he discovered a can opener instead of magnetic monopoles in the season three premiere of “The Big Bang Theory” http://goo.gl/kAEoOD.

Monday: Jupiter is three and a half fists held upright and at arm’s length above the south-southwest horizon at 9:15 p.m. That’s right after sunset so it will be a challenge. But if you know where to look, it is bright enough to be visible. A bigger challenge is the star Spica, a fist and a half to the lower left of Jupiter.

Tuesday: Venus is a little more than a half a fist to the left of the waning crescent Moon in the eastern sky at 5 a.m.

Wednesday: Tonight, 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 9:24 p.m. Pacific Daylight Time. Tomorrow is the first full day of summer.

Thursday: Saturn is two fists above the south horizon at midnight.

Friday: Nearly 400 years ago, Galileo viewed the Pleiades star cluster through his telescope and saw that the seven or so stars in the region visible to the naked eye became many more. There are two main types of star clusters. Open star clusters are groups of a few dozen to a few thousand stars that formed from the same cloud of gas and dust within our galaxy. Stars in open star clusters are young as far as stars go. Globular clusters are groups of up to a few million stars that orbit the core of spiral galaxies such as our own Milky Way. One of the most well known star clusters is the globular cluster in Hercules, an object that is fairly easy to find with binoculars. First find Vega, the bright bluish star five fists above the east horizon at 11 p.m. Two fists above Vega is a keystone shape. Aim your binoculars at the upper left hand star of the keystone. The globular cluster is one third of the way to the rightmost star of the keystone. It looks like a fuzzy patch on the obtuse angle of a small obtuse triangle. If you don’t know what an obtuse angle is, you should not have told your teacher, “I’ll never need to know this stuff”.

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.