Thursday, May 30, 2013

The Ellensburg sky for the week of 6/1/13

Saturday: The month of June is named after Juno, the queen of the Roman gods and the mythological protector of the Roman state. In ancient Rome, the month began when the crescent moon was first seen in the evening sky from Capitoline Hill in Rome. If we still started months this way, June wouldn’t begin until about two weeks from now. Celebrate the first sunset in June by actually watching it… and then keeping your gaze fixed on the west-northwest horizon until it is dark enough to see Jupiter, Venus, and Mercury in a line pointing away from the Sun. Jupiter will be less than a half a fist above the horizon when you first see it. Within a few days, it will be lost in the glare of the setting Sun. Venus is the brightest planet and Mercury is to the upper left of Venus.

Sunday: 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. And just to make it easy for you, a star that bears an Arabic name that means “the head” represents each 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.

Monday: Saturn is three fists above the south horizon at 10 p.m.

Tuesday: The bright star Arcturus is six fists above the south-southeast horizon at 10 p.m.

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: You can set your watch tonight by carefully observing Segin, the left-most star in the W-shaped Cassiopeia. It will be due north at exactly 10 p.m. However, another star in Cassiopeia is causing astronomers to doubt whether or not they can use neutron stars as the most precise known clocks in the universe. Neutron stars have such a precise spin rate that they are used to set clocks on Earth. But the neutron star called 1E 2259+586 (how’s that for a celebrity baby name) exhibited a spin glitch that astronomers had never seen before. To find out more about this new excuse for being late, go to

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

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