Thursday, July 9, 2015
The Ellensburg sky for the week of July 11, 2015
Saturday: Venus will really be negative for the next few nights. But, don’t feel bad for Venus. It is okay for a celestial object to be negative as long as we are referring only to its magnitude. The ancient Greek astronomer Hipparchus developed a system for rating the apparent brightness of stars and planets in which lower numbers refer to brighter stars and planets. In his initial scheme, all points of light in the night sky were classified from first magnitude, meaning bright, to sixth magnitude, meaning very dim. Modern day astronomers have made this scale more quantitative. Tonight and tomorrow, Venus has a magnitude, or apparent brightness rating, of -4.5. Sirius, the brightest star in the night sky, has a brightness rating of -1.5. That’s about the same magnitude as Jupiter is tonight. Venus is about a half a fist held upright and at arm’s length above the west-northwest horizon at 10 p.m. Jupiter is about a half a fist to the right of Venus. The star Regulus is less than a half fist to the upper left.
Sunday: Being in a coma is a bad thing. Looking at the Coma Star Cluster is a good thing. The Coma Star Cluster is an open cluster of about 50 stars that takes up more space in the sky than 10 full Moons. It looks like a fuzzy patch with the naked eye. Binoculars reveal dozens of sparkling stars. A telescope actually diminishes from the spectacle because the cluster is so big and the telescope’s field of view is so small. The Coma Star Cluster is in the faint constellation Coma Berenices (ba-ron-ice’-ez) or Queen Berenice’s hair. Queen Berenice of Egypt cut off her beautiful hair as a sacrifice to the gods for the safe return of her husband Ptolemy III from battle. The Coma Star Cluster is about three fists above the west horizon at 11:00 p.m.
Monday: Saturn is two and a half fists above the south horizon at 10 p.m.
Tuesday: New Horizons arrives at Pluto at about 4:50 a.m. PDT. But don’t be waiting by your computer for the latest images. First of all, it takes about five hours for the signal to get from Pluto to Earth. Second of all, New Horizons will be spending hours with its instruments pointed toward Pluto, not Earth. NASA TV will host a show from mission headquarters from about 5:30-6:15 p.m. PDT today to broadcast the celebration when the first signal from Pluto arrives. From 1:00 to 2:00 p.m. tomorrow, NASA TV will show the first close-up images from Pluto. For more information about NASA TV coverage of the event, go to https://goo.gl/oCtlGd. For more information about the mission, go to http://pluto.jhuapl.edu/.
Wednesday: Mercury is less than a half a fist above the northeast horizon at 5 a.m. If you have binoculars, you may be able to spot a much dimmer Mars to the lower left of Mercury.
Thursday: The long summer days remind us to take some time to safely observe the Sun. The best way to do that is to go to http://sdo.gsfc.nasa.gov/ and watch the great images and videos that come from the Solar Dynamics Observer, or SDO for short. We are just moving away from a sunspot maximum so the Sun has been very active lately. So what, you say? Sunspots and associated phenomena greatly influence the strength of solar flares. The strongest flares can affect satellites orbiting the Earth and even electronics on the Earth’s surface.
Friday: Say "Cheese". 165 years ago today, Vega, in the constellation Lyra the lyre, became the first star ever photographed. The photograph was done at the Harvard Observatory using the daguerreotype process. Vega is the third brightest nighttime star we can see in Ellensburg, behind Sirius and Arcturus. Vega is nearly straight overhead at 11:00 tonight.
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 http://nightsky.jpl.nasa.gov/planner.cfm.