Friday, April 1, 2011

The Ellensburg sky for the week of 4/2/11

Saturday: Some people in town today for the Yakima River Canyon Marathon may be looking for a little running inspiration. While nothing can take the place of a 20 mile long run for marathon preparation (I know), certain objects in the night sky are inspiring. In the Bible, Job specifically mentions the star Arcturus, or the bear keeper, to his friend as a sign of God's majesty. He describes God as that "Which maketh Arcturus, Orion, and Pleiades, and the chambers (constellations) of the south" (Job 9:9, King James Version). Whatever your religious beliefs, it is clear that Job was impressed with this very bright star. See the star that inspired Job about one and a half fists held upright and at arm’s length above the east horizon at 9 p.m.

Sunday: The bright star Deneb is a half a fist above the north horizon at 11 p.m.

Monday: Saturn is opposition tonight. That doesn’t mean that Saturn is a teenager. Opposition means that Saturn is on the opposite side of the Earth as the Sun. When an object is in opposition, it is at its highest point in the sky during the darkest time of the day. Thus, opposition is typically the best time to observe a planet. Saturn is about four fists above the south horizon at 1 a.m. It is two fists above the southeast horizon at 9 p.m.
If you remember this column from 2/23/2008, 3/8/2009, and 3/21/2010, you know that Saturn was also in opposition on those dates. Thus, it is in opposition about two weeks later each year. Two weeks is about one twenty-fourth of a year. This implies that it takes Saturn about 24 years to make one orbit around the Sun and get back in line with the same stars again. Saturn’s actual orbital period of 30 years matches this approximation quite well.

Tuesday: Give me a “W”. Cassiopeia, a W-shaped group of stars is two fists above the north horizon at 11 p.m.

Wednesday: Orion is getting lower and lower in the nighttime sky. Its second brightest star Betelgeuse is only one and a half fists above the west-southwest horizon at 11 p.m.

Thursday: This April, the hot topic in the tabloids is anyone in the Kardashian family. During April 2009, the International Year of Astronomy, the “Hot Topic” Astronomy was galaxies and the distant universe. When Galileo turned his telescope to the seemingly continuous band of light in the sky, he discovered it consisted of countless faint stars. This extended our celestial neighborhood from a few thousand stars to millions of stars. This neighborhood configuration lasted until the 1920’s when Edwin Hubble discovered that there are other galaxies with millions, or even billions, of stars just like our own galaxy. We may lose interest in celebrity break-ups but galaxies are always hot. At 11 p.m., you can see the thick band of the Milky Way galaxy starting at the northeast horizon, moving west through the bright star Deneb, through Cassiopeia, just above Betelgeuse and the Moon, under the feet of Gemini, and settling into the southwest horizon near Sirius, the brightest star in the nighttime sky. Follow this same track at this same time in a few nights when the Moon is not above the horizon to see the Milky Way even better.

Friday: Venus is a half a fist above the east horizon at 6 a.m.

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

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