Although the Sun is actually vastly larger than the Moon, they appear to be the same size when viewed from Earth and therefore produce spectacular total solar eclipses. Earth is the only planet in our solar system where this is true, and it's thanks to remarkable coincidences both in space and time.

The Sun and Moon are just the right combination of actual size and distance from Earth to make each appear to be the same size. This has not always been true, and it won't be true in the distant future. Long ago, the Moon was much closer to Earth and would have appeared larger than the Sun. And as the Moon continues to move slowly away from Earth, it will one day appear too small to fully cover the Sun. So another aspect of this cosmic coincidence is that it coincides with the presence of humans who can appreciate the phenomenon.