Wednesday, June 3, 2015

The Ellensburg WA sky for the week of 6/6/15

Saturday: This evening, Venus is as far away from the Sun in the sky as it will get this orbital cycle. What is this "farthest away" point known as? It is known as the planet’s greatest eastern elongation. Tonight is one of the best nights of the year to observe Venus because it is high in the sky at sunset and will be in the sky until nearly midnight. Venus is two fists held upright and at arm’s length above the west-northwest horizon at 10 p.m. Over the next two months, Venus will move toward the Sun in the sky. By the end of July, it will be lost in the glare of evening twilight.

Sunday: Jupiter is two and a half fists above the west horizon and a fist and a half to the upper left of Venus at 10 p.m.

Monday: 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”.

Tuesday: Saturn is about two fists above the south-southeast horizon at 10 p.m.

Wednesday: When it is sitting low in the western sky, many people mistake the star Capella for a planet. It is bright. It has a slight yellow color. But, Capella is compelling on its own. It is the fourth brightest star we can see in Ellensburg. It is the most northerly bright star. It is a binary star consisting of two yellow giant stars that orbit each other every 100 days. At 10 p.m., Capella is two fists above the north-northwest horizon. If you miss it tonight, don’t worry. Capella is the brightest circumpolar star meaning it is the brightest star that never goes below the horizon from our point of view in Ellensburg.

Thursday: What you see with the naked eye isn’t all that can be seen. While astronomers can learn a lot from observing the sky in the visible wavelengths, many celestial objects radiate more light, and more information, in wavelengths such as radio, microwave, infrared, ultraviolet, x-ray, and gamma ray. In 2009, NASA launched the Wide-field Infrared Survey Explorer (WISE) to study objects that radiate in the infrared range such as asteroids, cool dim stars, and luminous galaxies. For an interesting comparison of how different wavelengths show different aspects of a galaxy, go to If it weren’t for infrared telescopes such as WISE, astronomers would not know about the significant amount of dust in galaxies.

Friday: Summer is nearly here. How do I know? Because kids are getting out of school. Because I read the fine astronomy column in the Daily Record. (How’s that for an odd self reference.) Also, because the Summer Triangle is fairly high in the eastern sky at 10:30 p.m. Vega, the third brightest star visible from Ellensburg, is about five fists above the east horizon. Deneb, at the tail of Cygnus the swan is about three and a half fists above the northeast horizon. The third star in the triangle, Altair, in Aquila the eagle is two fists above the east horizon.
If you want to put somebody off, tell her or him to wait until Deneb sets. At Ellensburg’s latitude of 47 degrees, Deneb is a circumpolar star meaning it never goes below the 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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