Thursday, June 30, 2011

The Ellensburg sky for the week of 7/2/11

What's up in the sky 7/2/11

Today: Monday night, while you are looking at an explosion of fireworks, the NASA spacecraft Kepler may be looking at an “explosion” of exoplanets. So far, Kepler has found 16 planets whose presence has been confirmed by other means and evidence of 1,235 planet candidates. Something is called a planet candidate when the light from a star being observed by Kepler dims in a systematic way. Astronomers still need to compare the pattern of dimming with the potential pattern of star wobble caused by being tugged on by one or more planets before they can say for certain that they have actually found planets orbiting these stars. But if even half of these stars show the characteristic wobble, it will more than double the number of planets known to orbit other stars, also known as exoplanets. And this is only the beginning. The Kepler spacecraft is monitoring the brightness of over 156,000 stars in the constellations Cygnus the swan and Lyra the lyre. This region is midway between the bright stars Deneb and Vega. It is about the size of your hand held at arm’s length and is about six fists held upright and at arm’s length above due east at 11 p.m.

Sunday: 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 Earth-Sun distance is 152.1 million kilometers tomorrow. This is called aphelion from the Greek prefix “apo” meaning “apart” and Helios, the Greek god of the Sun.

Monday: The little king gets mooned! Regulus, Latin for “little king”, is less than a fist from the upper right-hand portion of the Moon at 9:30 p.m.

Tuesday: 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.

Wednesday: The elusive Mercury is a half a fist above the west-northwest horizon at 9:45 p.m. It will be hard to see in the glow of the setting sun. But I know you can find it. I have much more faith in you than in that person standing next to you reading the celebrity magazine. “Best Beach body!” Puh-lease.

Thursday: In 1982, the Australian rock group Men at Work sang “Isolation, rows and rows of cars. Isolation, like Jupiter and Mars” in their song “Catch a Star”. Mars is certainly not isolated this week. It is about a half a fist to the upper left of the open star cluster called the Hyades cluster. They are one and a half fists above the east-northeast horizon at 4:30 a.m. Jupiter, on the other hand, is in a portion of the sky with no other bright stars. It is three fists above the east-southeast horizon at this time.

Friday: Saturn is two and a half fists above the southwest horizon at 10 p.m.

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

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