 A total solar eclipse is an incredibly moving experience. In the continental U.S. there's going to be an amazing event on August 21st, 2017. A total eclipse of the sun. Well a total solar eclipse is this incredible phenomenon that happens because of the sun being 400 times bigger than the moon, but also 400 times farther away. Suppose this tennis ball is the sun and the ping-pong ball is the moon, and I'm a person on earth looking at the two. If the moon is a bit too far away in its elliptical orbit, then it doesn't quite block the sun, and if it's too close, then it blocks not only the bright disc of the sun, but the inner corona as well. But if I line them up so that the ratio of distances is 2 to 1, that's the same as the ratio of sizes, and then they look the same size in the sky. So the ping-pong ball moon blocks the entire tennis ball sun. Nowhere else in the solar system is that the case. So if aliens were to visit our solar system, I claim they should visit earth at the time and location of a total solar eclipse, and they would leave very happy. The Space Sciences Lab, together with Google and a number of institutions, has decided to document the eclipse over the hour and a half that the shadow crosses the continental US. We've got about 1,000 serious photographers taking good quality images of the sun, and anyone else who wants to contribute can do so as well. By having many images of the corona over the course of an hour and a half, we'll be able to examine the changing structure of the corona, and that's important because the satellites orbiting earth right now can't monitor changes in the inner corona for technical reasons, but from the ground we can. Scientists want to understand the structure of the corona better because it tells us about the inner workings of the sun. There are solar flares and coronal mass ejections that then interact with earth's magnetic field and can cause power blackouts. So the better we understand the sun, the more we will be able to respond to and indeed even predict these tremendous outbursts from the sun's surface. And that's something that citizen scientists will actually be able to help out with. If you don't make an attempt to go to the location where a total solar eclipse is happening, one will visit you roughly every 380 years. So this is a real opportunity for tens of millions of Americans and others throughout the world to see the total solar eclipse.