Thursday, June 25, 2009

The Ellensburg sky for the week of 6/27/09

Saturday: Saturn is about one fist held out at arm’s length to the upper right of the Moon at 10 p.m.

Sunday: When people find out that you read this column, they may ask you all sorts of tough astronomy questions such as “Where can I see the Milky Way?” That one is easy. Just look in the mirror. We are all part of the Milky Way. The center of the Milky Way galaxy is in the direction of the constellation Sagittarius, about one and a half fists above due south at 11:30 p.m. The Milky Way is NASA’s “Go Observe” object for July. For more information, go to

Monday: Today’s first quarter moon is in… is in…. Actually, today’s first quarter moon is not even visible. The first quarter moon occurs one week after the new moon when the Sun, Earth, and Moon make a 90 degree angle. The right half of the Moon is illuminated. This month they form the right angle at 4:30 this morning when the Moon is below the horizon. That means that tonight’s moon will be more than half lit and last night’s moon was less than half lit. Look for this waxing gibbous Moon two fists above the southwest horizon at 10 p.m.

Tuesday: The constellation Cepheus the king (husband of Cassiopeia the queen) is about four fists above the northeast horizon at 11 pm. Cepheus is about one and a half fists above Cassiopeia. Cepheus looks like a house on its side with the roof peak pointing towards the west. Cassiopeia and Cepheus revolve around the North Star every night like a happy couple going through life together.

Wednesday: At midnight, Jupiter is about a half a fist above the east-southeast horizon.

Thursday: You have two good reasons to take a nap today. The first reason is that you will probably stay up late this weekend to watch many bright objects move rather quickly across the sky. The second is that you’ll want to stay up late tonight to watch a single bright object move rather quickly across the sky. The International Space Station will appear one fist above the east-northeast horizon at 12:25:09 tomorrow morning. It will move toward the east-northeast horizon for seven seconds before disappearing. If you miss this short trip, you have another chance at 1:56:35. This time, a much brighter ISS will appear three fists above the west-northwest horizon and move toward the east-northeast horizon for four minutes. How much would you pay for this experience? Wait, don’t answer yet. You have even one more chance at 3:30:40 tomorrow morning when the ISS appears one fist above the west-northwest horizon and moves toward the east-northeast horizon for five minutes. For more information about when you can see the International Space Station or any other human-made satellite throughout the year, go to

Friday: Are you feeling warm this time of year? Don’t blame the distance between the Earth and the Sun for the hot days of summer. The Earth is actually farther away from the Sun during the Northern Hemisphere winter than during the summer. Today, the Earth is at aphelion. Apo- is Greek for “away from” or “far from” and helios is Greek for Sun. So at aphelion, the Earth is farther from the Sun than on any other day. The Earth is about 3.3% farther from the Sun today than it is in January.
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 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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