“Perfect” total solar eclipses like those experienced from Earth are incredibly rare phenomena. No other planet in our Solar System has them, and there’s no good reason we should have them. It’s just a marvelous coincidence that the Sun is both 390 times larger than the Moon and 390 times farther away from Earth, causing the Sun and the Moon to have essentially the same apparent (angular) size in the sky. We got remarkably lucky! And in fact, the Moon is slowly receding from Earth, appearing progressively smaller in the sky—so total solar eclipses are becoming even more rare, and they won’t be possible at all in about half a billion years.
That we Earthlings get to see this amazing spectacle is indeed incredibly special! But even on Earth, at a given location, roughly 400 years go by between consecutive total solar eclipses, on average. This means that a total solar eclipse is unlikely to occur where you are by chance; instead, you must travel to the right location at the right time, and that’s part of the fun. You can explore the world while chasing total solar eclipses!
–Text by Alex Filippenko, total solar eclipse enthusiast and Professor of Astronomy at the University of California, Berkeley. Professor Filippenko will be the guest eclipse expert on Total Solar Eclipse of 2013: Morocco to Cape Verde.
–Photos by Rick Fienberg (top) and Ethan Daniels (bottom)