Wednesday, June 16, 2010

The Ellensburg sky for the week of 6/19/10

Saturday: Summer is nearly here. How do I know? Because my kids are home from school. Also, because the Summer Triangle is fairly high in the eastern sky at 10 p.m. Vega, the third brightest star visible from Ellensburg, is about five fists held upright and at arm’s length 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 them to wait until Deneb sets. At Ellensburg’s latitude of 47 degrees, Deneb is a circumpolar star meaning it never goes below the horizon.

Sunday: Venus, the brightest planet, looks like it is in danger of being stung by a bee tonight. It is right above the open star cluster known as the Beehive Cluster. This cluster is about 600 million years old and is about 600 light years away. (Oops, I guess the bees can’t fly that far. Also, there is nothing for them to beat their wings against in space. Finally, there are no bees in the Beehive Cluster. Well, that storyline failed.) Venus is the bright point of light one fist above the west-northwest horizon at 10 p.m. The cluster will be easily visible in binoculars below Venus.

Monday: Today is the first day of summer, the day that the Sun reaches its highest declination (the official name for sky latitude) of 23.5 degrees above the celestial equator. The celestial equator is the line that divides the northern sky from the southern sky. In Ellensburg, the Sun is about seven fists held upright and at arm’s length above the south horizon at 1:00 p.m. (noon standard time). Contrary to popular belief, the Sun is never straight over head in Ellensburg or anywhere else in the 48 contiguous states. The northernmost portion of the world where the Sun can be directly overhead is 23.5 degrees north latitude. In ancient times, the Sun was in the constellation Cancer the crab on the first day of summer. Hence, 23.5 degrees north latitude has the nickname "Tropic of Cancer". Because the Earth wobbles like a spinning top, the Sun's apparent path through the sky changes slightly over time. Now, the Sun is in the constellation Taurus the bull on the first day of summer. However, citing the high cost of revising all of the science books, geographers are not changing the name of 23.5 degrees north latitude to "Tropic of Taurus". The first day of summer is often called the summer solstice. However, astronomers refer to the summer solstice as the point in the sky in which the Sun is at its highest point above the celestial equator. Thus, summer starts when the Sun is at the summer solstice point. This year, that happens at 4:36 a.m.

Tuesday: Summer is the season of the horse and rider here in Ellensburg. But every night of the year is the season of the horse and rider in the Ellensburg sky. Mizar and Alcor, two stars at the bend of the Big Dipper’s handle, were known to the ancients as the horse and rider because dim Alcor “rides” just above brighter Mizar in the sky. Since the Big Dipper is circumpolar from Ellensburg’s latitude, it never goes below the horizon. Tonight, Alcor and Mizar are seven fists above the northwest horizon at 10:30 p.m.

Wednesday: Jupiter is two and a half fista above the southeast horizon at 4 a.m.

Thursday: Saturn is two and a half fists above the west-southwest and Mars is one and a half fists above the west horizon at 10:30 p.m.

Friday: A few days ago, I wrote about Mizar. Don’t confuse it with its rhyming brother Izar in the constellation Bootes. Izar is also a binary star with about the same apparent brightness. And both were featured in different episodes of Star Trek. Izar was featured in the Star Trek episode “Whom Gods Destroy” from the original series. It is the base of Fleet Captain Garth, a former big shot in the federation and one of Kirk’s heroes before he went insane. Garth kidnaps Kirk and Spock before eventually being out smarted. Mizar doesn’t play as big a role in its episode. It is the star of the home world of one of the alien species in The Next Generation episode “Allegiance”. Izar is one fist above the bright star Arcturus and seven fists above the south horizon at 10 p.m. Mizar is seven fists above the northwest horizon at this time.

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

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