Friday, July 3, 2009

The Ellensburg Sky for the week of 7/4/09

Saturday: Do you want to take a chance on seeing some really big fireworks? Don’t go to those wimpy firecracker shows. Find the hypergiant star Rho Cassiopeiae. Astronomers think that Rho Cassiopeiae will likely go supernova (explode) in the near future. Of course, for stars, near future might mean July 4, 2009. It might mean July 4, 52,009. Rho Cassiopeiae is in the constellation Cassiopeia the queen. At 11:00 tonight, Cassiopeia looks like the letter “W” about three fists held upright and at arm’s length above the northeast horizon. Rho Cassiopeiae is about a finger’s width to the right of the rightmost star in the “W”.

Sunday: Now that “Jon and Kate Plus 8” is taking a break, you should get up early and watch Mars and Venus Plus 7”. That’s right. Those lovely, overworked planets are spending time with the seven sisters for the next few mornings. Mars, Venus, and the seven sisters, also known as the Pleiades, make a small triangle about one fist above the east horizon. Venus, the brightest point of light in the sky, is at the bottom of the triangle. Mars is in the upper right, about a half a fist from Venus. The Pleiades, an open star cluster consisting of seven naked eye stars, is a half a fist to the upper left of Venus.

Monday: The full moon occurs early tomorrow morning at about 2:20 a.m. When the Moon is full, it is difficult to see dim objects in the sky because of the sky glow. But why struggle to find dim objects when there is so much to see on the big, bright object in front of you? The lunar crater called Tycho is best seen during a full Moon. Tycho was formed about 109 million years ago when an asteroid struck the Moon, leaving a crater over 50 miles in diameter and ejected dust trails that radiate out hundreds of miles in all directions. For more lunar highlights, go to, a resource of the Night Sky Network.

Tuesday: Jupiter has a planetary neighbor in the late night sky for a few nights. Neptune, the farthest planet from the Sun – take that you Pluto lovers – is above Jupiter for the next few weeks. At midnight, Jupiter, the brightest point of light in the sky, is one fist above the southeast horizon. You’ll need binoculars to see Neptune, the dim point of light right above Jupiter. There is also a star that is brighter than Neptune but much dimmer than Jupiter right above Jupiter in the sky.

Wednesday: Saturn is one and a half fists above the west horizon at 10 p.m.

Thursday: Jupiter is about a half a fist to the lower left of the Moon in the low southeast sky at 11:30 p.m.

Friday: Hot enough for you? Don’t blame the Earth-Sun distance. Surprisingly, the overall temperature of the Earth is slightly higher in July, when the Earth is farthest from the Sun, than in January, when it is closest. That’s because in July, the Northern Hemisphere is tilted towards the Sun. (This is the real cause of the seasons.) The Northern Hemisphere has more land than the Southern Hemisphere. Thus, in July, the large amount of Northern Hemisphere land heats up the entire Earth about two degrees Celsius warmer than in January. In January, the watery Southern Hemisphere is tilted toward the Sun. But, water does not heat up as fast as land so the Earth is a few degrees cooler.

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

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