Citizen science and adventures with eclipses

Last night I didn't get to bed until 4 am. Along with a couple hundred other people, I hung out at the Chabot Observatory, watching the Earth slide in between the Sun and the Moon. One of the Observatory's telescopes was open, and several people brought their own 'scopes, some homemade. The viewpieces were big enough to allow me to take some pictures through the telescopes.

The focus is a bit off there, but you can see the craters and plains of the Moon's surface, and at the lower right corner, you can see the surface starting to darken as the penumbra of the Earth's shadow begins to cross it.

It's astounding what you can do with just a tripod, a mid-range digital camera, and a telephoto extender. The telescope spins the image around, so the shadow in this image is at the upper left, instead.

Below the fold, more photos of a late night, high above Oakland.

Here are a few of the enthusiasts, including one high school astronomy class, on a field trip the first day of school, and a bunch of amateur astronomers with their telescopes.

Because of the size of the sun, the Earth blocks only some of it at first. That partial shadow (seen above the fold) is called the penumbra. The total shadow, seen here, is called the umbra. The curvature of the shadow makes it possible to calculate the relative size of the earth and the moon, allowing early astronomers to estimate distances between the Earth and the Moon.

Once the Moon enters the umbra, the eclipse is total. The Moon typically turns red during this phase, though the particular shade of red varies from eclipse to eclipse. It varies because, as one person at Chabot put it, the red is the reflection of every sunset and sunrise on Earth. Just as every sunset is different, every reflected sunset differs.

It was wonderful to see that there are so many people willing to stay up until 4 am to watch an event like this, and it was great to see Chabot working so hard to educate those people who showed up. A local TV news affiliate was filming, and hoping to put together a package for national distribution. I hope the people watching at home enjoyed it as much as I did.