Thursday, September 7, 2017
The Ellensburg WA sky for the week of 9/9/17
Saturday: Today: “Excuse me, do you have the time?”
“No, but the Big Dipper does.”
You can use the orientation of the Big Dipper to tell time with a precision of about 15-30 minutes. First, find the two stars at the far end of the Big Dipper cup, the stars that do not touch the handle. Draw an imaginary line segment starting at the North Star and passing through the two Big Dipper cup stars. Now, draw a big circle around the North Star. Your circle is a 24-hour clock. Number the circle from 0 hours at the top, counterclockwise to 12 hours at the bottom of the circle, and back up to 24 hours at the top. (O hours and 24 hours are the same on this clock because the day is 24 hours long.) The hour number on the big circle closest to where your imaginary line intersects this circle is called your raw time. Due to the location of the Big Dipper compared to the rest of the stars, the time nearest the intersection (the raw time) is correct for March 6. For any other night, subtract two times the number of months the current date is after March 6 from the raw time. For example, let’s say the imaginary line between the North Star and the Dipper stars is pointed to the right. That means the raw time is 18 hours or 6 p.m. If you made this observation on October 6, which is seven months after March 6, you would subtract two times seven or 14 hours from the raw time. Thus, the time for November 6 is 18 hours minus 14 hours or 4 hours. In other words, 4 a.m. Don’t forget to convert for daylight savings time if needed. For a more complete explanation on how to do the Big Dipper clock math, go to http://goo.gl/02HmA. If you prefer a more visual tool, and a fun project to do with your kids, there is a simple “star clock” template and instructions at http://goo.gl/SFKrE. Use this paper star clock whenever you watch is broken.
Sunday: Jupiter is a half a fist held upright and at arm’s length above the west-southwest horizon at 8 p.m. Saturn is two fists above the south-southwest horizon at this time. Both of these planets can be seen as disks even through a small backyard telescope. The reddish bright star Antares is to the lower right of Saturn, a little more than one fist above the south-southwest horizon. Even though Antares is a supergiant, it still looks like a point through most telescopes. Most, but not all. Astronomers used the European Space Agency Very Large Telescope Interferometer to create an image of the surface of Antares. To see that image for yourself, go to https://goo.gl/Y4G4WF.
Monday: The calendar says summer is nearing an end. School starting says summer is nearing an end. The summer triangle in the sky begs to differ, as it is still high in the sky. Vega, the brightest star in the triangle, is a little bit south of straight overhead at sunset. Deneb is six and a half fists above the east horizon and Altair is five fists above the southeast horizon.
Tuesday: In 1987, the rock group Def Leppard sang “Pour some sugar on me, in the name of love. Pour some sugar on me, come on fire me up”. In 2012, some European astronomers “found some sugar near stars, they were very young. Found some sugar near stars, out where planets formed.” Astronomers observed molecules of glycolaldehyde, a simple form of sugar, in the disk of gas and dust orbiting young binary stars. This is the first time astronomers have found this simple sugar so close to a star indicating that organic molecules can be found in planet-forming regions of stars. For more information, go to http://goo.gl/tfwy1.
Wednesday: The morning sky is packed with planets. At 6 a.m., Venus is two fists above due east. One fist above the horizon, a little bit south of east, sit three bright objects making a diagonal line from Venus to the rising Sun. The one in the middle is Mercury, the brightest of the three. Just above Mercury is the star Regulus and just below Mercury is Mars.
Thursday: Had the script been written a little differently for a well-known Robin Williams movie, we might have heard Mr. Williams shout, “Goooood Morning Orion the hunter”. Orion is typically thought of as a winter constellation. But, it makes its first appearance in the early morning summer sky. The lowest corner of Orion’s body, represented by the star Saiph (pronounced “safe”), rises at 2 a.m., well before the Sun. By 6 a.m., Orion’s belt is nearly four fists above the south-southeast horizon.
Friday: Stuart Sutcliffe was the fifth Beatle. d’Artagnan was the fourth Musketeer. Ophiuchus is the thirteenth constellation in the Zodiac. The Zodiac consists of all the constellations that the Sun appears to line up with as the Earth’s celestial perspective changes throughout its annual orbit. You know twelve constellations in the Zodiac because they are the 12 horoscope signs. But the Sun also lines up with Ophiuchus for about two weeks every year. You can spend some time with Ophiuchus tonight. The center of the coffin shaped group of stars is three fists above due southwest at 9 p.m.
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.