If you didn’t see the total eclipse on August 21, 2017, you may be wondering, “How did I miss it? It was supposed to be a total eclipse.”

Well, a total eclipse happens only when the moon passes perfectly in front of the sun, blocking its view from Earth. Because the moon is so much smaller than the sun, the “path of totality,” where the sun is completely obscured, is quite narrow.

This may be easiest to imagine if you picture the view from space. You’d see a small moon shadow 70 miles wide cast upon the surface of Earth and moving across it at 1,500 miles an hour.

That moon shadow crossed the U.S. from Oregon to South Carolina, passing over 50 million people who live there—and several million more who traveled there to see it. And I was one of them.

Here’s what we saw:

The moon shadow raced forward, eventually engulfing us. Darkness fell. The temperature dropped 10 degrees. Sunset descended on all horizons. Birds stopped chirping, and night insects began.

It was an amazing, almost unnerving experience.

Then as quickly as it started, it was over, and the moon shadow raced on.

Now, if I’m making you more disappointed that you missed it, don’t be. Seven years from now, a total eclipse will return. Because of the orientation of the sun, moon, and Earth, the path of totality will be wider, and it will cross from Texas to Maine.

So set a reminder on your calendar for April 8, 2024.