Well, if you’re speaking of total solar eclipses, one happens about every year or every other year, somewhere on Earth.
However, you have to be situated in a very narrow strip of land (called the ‘path of totality‘) if you want to see the total phase of the eclipse. Otherwise, all you see (with your eclipse glasses, of course!) is a pretty boring partial eclipse. And that strip of land is generally VERY far off the beaten path – like Mongolia, or the Sahara desert, or the ocean somewhere. Because of this, very few people (as a percentage of the overall population) have ever seen a total solar eclipse.
There has not been a total solar eclipse whose path of totality touched the mainland USA since 1979! That’s right – the 1992, 2012, and 1994 eclipses were annulars, and 1991‘s “USA” totality only touched Hawaii. 1986 was total (kind of…), but for the US, it was only partial. And the Christmas Day 2000 eclipse was partial for everyone on Earth. And on and on – trust us, there has not been a path of totality touch the mainland USA since 1979.
That’s why this one is so exciting – it’s been a LONG time since the mainland USA saw totality, and it’s coming – on August 21!