As millions flock to the path of totality across the U.S. for this once-in-a-generation event, you should know it’s going to happen again in less than two years.

However, you won’t notice. It’s going to happen over the Pacific Ocean and skirt the southern edge of Argentina. In fact, eclipses occur around the globe roughly every 18 months, according to Popular Science.

We’ve had 9 total solar eclipses since 2001.

So why do they feel so rare?

It can take hundreds of years for eclipses of the sun to pop up in the same place. But if you are willing to travel wherever you need to go, you can see them a lot more often, although not all of them happen in places you can easily get to.

There’s even been a double eclipse — recently.

Less than a year ago, NASA scientists caught both the Earth and the moon crossing in front of the sun. The Earth blocked out the sun completely from the perspective at NASA’s Solar Dynamics Observatory at the same time the moon started to cross in front of the sun.