I remember seeing the mock-up of this on my old dos-based astronomy program when I was in 5th grade. The computer program made it out to be the most important thing that would happen in the sky for hundreds of years, and let you ”watch” the transit from different viewing points around the earth. So what’s all the fuss about anyway?

Well, I’ll let you read the whole story on your own time, but the general idea is that these transits occur only twice in anyone’s lifetime, spaced 8 years apart. This morning’s transit is the first one that any living human has seen, so we’re all seeing something new together. The last recorded transit occured in the late 19th century, and the Brits sent people out all over the world to record the times of the ”contacts.” These times represent the times when the disk of Venus makes contact with the edges of the sun. However, just like during our own sunrise and sunset, the atmosphere of Venus will refract the sunlight slightly, creating a slight distortion between Venus and the sun’s edge that makes it very difficult to record the exact contact times. Had these times been recorded a bit more accurately in the 1800’s, the astronomers could have very precisely calculated the size of the solar system. However, the actual times recorded by the various watchers around the earth were off by 20-40 seconds, making the actual calculated size of the solar system incorrect. However, even with the problems, the Brits gave a pretty good try at deploying a global array of telescopes all pointed in the same direction in a time when communication was by horse courier and long distance travel was by sail.