On April 8, 2024, millions of Americans will be able to see a rare celestial occurrence: a total solar eclipse.

It’s going to be awesome. If you’re in the center of the moon’s shadow, known as the totality, the sky will go dark for a few minutes in the middle of the day. The temperature will drop, stars will appear, and birds will become confused and start chirping their nighttime songs.

And it’s all because of a cosmic coincidence: From the Earth, the moon and the sun appear to be roughly the same size.

This will be the last total solar eclipse over the contiguous United States for 21 years. Don’t miss it!