Log, Jul 14, 2006
51 people. The Big Apple Circus is at Ninigret Park this Friday. This makes for larger than usual crowds and more light than normal. I don't begrudge the Circus its week of lights since it is a major supporter of the Park. However it does limit what we can see. A lot of people showed up very early hoping to see something before the show. Some were surprised to discover that we aren't open while the sky is bright blue. In summer, sundown doesn't mean darkness, but at least Jupiter is well placed and it was possible to see it quite well in twilight.We went after a number of bright targets - Jupiter and its 3 moons [Europa hid behind Jupiter all night], the lovely pair of stars known as Albireo, the fine globular cluster M22, the Lagoon Nebula (M8) and we made an attempt at the Ring Nebula (M57) only o find it too high to escape the dome shutter.I did a fair amount of star hopping. No sooner would one group leave than another would arrive. I must have pointed out the Summer Triangle five times last night. And what would a year be without someone staunchly defending the mistaken idea that Polaris is the brightest star in the sky? I would love to get the guy who started that rumor and force him to look at the sky. It simply isn't the brightest star. In fact it doesn't even make the Top 10 nor even the Top 50! Its sole claim to fame is that it sits almost perfect above the North Pole and acts as a very fine directional pointer.I was talking to a few folks near closing about basic facts and figures that you can calculate for yourself. Some things are difficult to be sure but other things are easy to calculate for yourself to a reasonable accuracy. For example we were talking about everything moving about the solar system and the whole solar system moving about the center of the Milky Way Galaxy. The question came up about how fast the Earth moves around the Sun. Well the exact answer depends upon the point the Earth is in its orbit (It goes fastest when it is closest to the Sun and slowest when it is farthest). However, you can come up with a very good approximation by knowing how many miles there are in the Earth's orbit and how many hours there are in a year. From high school math, we know that a circle's circumference is "pi" times the diameter. The distance from the Earth to the Sun is about 93,000,000 miles. So the length of the Earth's orbit (circumference) is about 3.1416 times 93,000,000*2 miles or a miles. A year is about 365.25 days times 24 hours or 8766.0 hours. This means the Earth rotates around the Sun at about 66,700 miles per hours. Makes you wonder why we don't fall off! More seriously, it explains why hitting an asteroid head on can cause a disaster like the extinction of the dinosaurs some 65 million years ago.-Les Coleman
