Have you ever seen the sky go dark in the middle of the day? On April 8, 2024, millions of people watched the moon slide between Earth and the sun. The sky darkened in the afternoon, stars appeared, and temperatures dropped. It was a total solar eclipse. A total solar eclipse happens because of an amazing coincidence. The sun is about 400 times wider than the moon, but also 400 times farther from Earth. This means the moon appears the same size as the sun in our sky. When the moon passes in front of the sun, it blocks the bright surface completely. The area where this happens is called the path of totality. On April 8, this path was about 115 miles wide. People inside the path saw the sun's corona. The corona is the outer layer of hot gas that is normally invisible. The sun's surface is so bright that it hides the corona. The corona looked like a glowing white halo. Scientists use eclipses to study the corona because it is the only time they can see it without special instruments. The next total solar eclipse visible from the United States will not happen until 2044.