Thursday, October 17, 2019

The Ellensburg, WA sky for the week of October 19, 2019

Saturday:  Mercury will be as far away from the Sun in the sky as it will get this orbital cycle. This "farthest away" point is known as the planet's greatest elongation. Since Mercury is in the evening sky, it is east of the Sun and this occurrence is called the greatest eastern elongation. This evening, Mercury is just above the southwest horizon at 6:30 p.m., to the left of the much brighter Venus. Over the next few weeks, Mercury will move toward the Sun in the sky. By mid-November, it will be visible in the morning  sky.

Sunday: Jupiter is about one fist held upright and at arms length above the southwest horizon at 7:00 p.m. At this same time, Saturn is two fists above the south-southwestern horizon.

Monday: The Orionid meteor shower consists of the Earth colliding with pieces of the remains of Halley's Comet's tail. This shower peaks after midnight for the next two nights. This is not a meteor shower that typically results in a meteor storm. There will be about 15-20 meteors per hour, many more meteors than are visible on a typical night but not the storm that some showers bring. Also, the Last Quarter Moon will out most of the night and obscure the dimmer meteors with its light. The best time to observe will be near dawn, after moonset. Meteor showers are named after the constellation from which the meteors appear to originate. These meteors appear to come from a point in Orion, the hunter. This point is about one fist held upright and at arm’s length above due east at midnight. You can follow this point throughout the night as it will remain one fist above the prominent reddish star Betelgeuse (pronounced Bet'-el-jews). The Orionid meteors are fast - up to 40 miles per second. If you fall asleep tonight, you can catch the tail end of the shower every night until early November. For more information, go to http://earthsky.org/?p=2147 

Tuesday: Mars is half a fist above the east-southeastern sky at 6:30 a.m.

Wednesday: Last week, the Hubble Space Telescope got the first close-up view of a comet from another star system. Comet 2I/Borisov was discovered by amateur astronomer Gennady on August 30, 2019 as the second interstellar object ever confirmed. 2I is the new official designator for the second interstellar object. Astronomers know it is from another star system because it is going way too fast, 110,000 miles per hour, to be gravitationally bound to the Sun. Read and watch more about the discovery at https://www.nasa.gov/feature/goddard/2019/hubble-observes-1st-confirmed-interstellar-comet.

Thursday: Rho Cassiopeiae is the most distant star that can be seen with the naked eye by most people. It is about 8,200 light years away. That means that the light that reaches your eyes from that star left over 8,000 years ago, before the beginning of time according to the Byzantine calendar. Rho Cassiopeiae is six fists above the northeast horizon at 8 p.m., just above the zigzag line that marks the constellation Cassiopeia.

Friday: Along with the not-so-subtle drug reference in their name, The Doobie Brothers could have made an astronomy reference in their song lyrics if they would have written: “Old Earth water, keep on rollin’, Mississippi moon won’t you keep on shining on me.” Astronomers now think that some of the water on Earth may be older than the Solar System. The chemical signature of the water indicates it came from a very cold source, just a few degrees above absolute zero. The early Solar System was much warmer than this meaning the water came from a source outside the Solar System. For more information about the old Earth water, go to http://goo.gl/QsEu5P.


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

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