Wednesday, May 30, 2012

The Ellensburg sky for the week of 6/2/12

Saturday: In 1979, the group Foreigner recorded the song “Head Games”. They could have been singing about the constellations Hercules and Ophiuchus when they said “head games, it’s just you and me baby, head games, I can’t take it anymore” because the heads of these two constellations have been right next to each other in the nighttime sky for all of human history. Each head is represented by a star bears an Arabic name that means "the head." In Hercules, it's Ras Algethi (head of the kneeler); in Ophiuchus, Ras Alhague (head of the serpent charmer). At 11 p.m., Ras Alhague, the brighter of the two, is a little more than four fists held upright and at arm’s length above the southeast horizon. Ras Algethi is about a half a fist to the upper right of Ras Alhague.

Sunday: At 10 p.m., reddish Mars is four fists above the southwest horizon and orangish Saturn is three and a half fists above the south horizon. Don’t confuse Saturn with the bluish and slightly dimmer Spica that is a half a fist below it.

Monday: Set your alarm for early this morning so you don’t miss the partial lunar eclipse. The full moon will move into the Earth’s shadow at about 3 a.m., Pacific Daylight Time. By the eclipse peaks at 4 a.m., the Earth’s shadow will cover more than one third of the moon.

Tuesday: You are a busy person. I understand that. But will you be busy in 105 years? That is the question to ask yourself if you are thinking of skipping the CWU Astronomy Club Venus Transit viewing event today from 3:00 pm to sunset. CWU astronomy students will be on the corner of 18th Avenue and Walnut Street with properly filtered telescopes and other safe viewing devices to observe Venus pass across the face of the Sun for the last time in 105 years. There will be prizes, fun, and education. Of course, education is its OWN prize and fun. You should NEVER look directly at the Sun without proper protection.
There is a CWU parking lot about a block away that is free all day and a CWU parking lot across the street that is free after 4:30. See the campus parking map at for more details. For the most up-to-date information about CWU Astronomy Club events such as this, go to (You don’t need to have a Facebook account to view this page.)

Wednesday: 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”.

Thursday: It is often said that Earth is a water world because about 70% of the Earth’s surface is covered by water. What would it look like if all that water on the surface were gathered up into a ball? That “ball” would be about 700 km in diameter, less than half the diameter of the Moon. The Astronomy Picture of the day shows us right here

Friday: Mercury is a half a fist above the northwest horizon at 9:30 p.m.

The positional information in this column about stars and planets is typically accurate for the entire week.

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