Thursday, October 18, 2018

The Ellensburg WA sky for the week of 10/20/18

Saturday:  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 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

Sunday: The joint European/Japanese space agency mission to Mercury called BepiColombo just launched. There is an overview of the mission at But why name the mission BepiColombo? Giuseppi (Bepi) Colombo was a pioneer in studying Mercury. He made the critical calculations to insure that NASA’s Mariner 10 mission in 1974 would be a success, teaching us nearly everything we knew about Mercury until recently.

Monday: Halloween is coming soon so make sure you load up on peanut clusters, almond clusters, and open star clusters. That last one will be easy (and cheap… actually free) because two of the most prominent open star clusters in the sky are easily visible in the autumn sky. The sideways V-shaped Hyades Cluster is two fists above due east at 10 p.m. Containing over 300 stars; the Hyades cluster is about 150 light years away and 625 million years old. The Pleiades Cluster, a little more than three fists above due east, is larger at over 1000 stars and younger. Compared to our 5 billion year old Sun, the 100 million year age of the Pleiades is infant-like. The moon will help you find these clusters. This morning at 6:30 a.m., the Pleiades cluster is less than one fist to the upper right of the moon and the Hyades cluster is about one fist to the upper left of the moon. Tomorrow morning, the moon sits in the “V” of the Hyades cluster.

Tuesday: Jupiter is a half a fist above the southwest horizon at 6:30 p.m.

Wednesday: 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

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: At 7 p.m., Saturn is one and a half fists above the south-southwest horizon and Mars is two fists above the south-southeast horizon.

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

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