Why are there total solar eclipses?

The Sun is 400 times larger than the Moon. However, it is also 400 times farther from Earth. For this reason, the Sun and the Moon appear to be the same size when viewed from Earth. Since the Moon orbits around Earth, there are times when it perfectly aligns in front of the sun. The bright disk is completely covered, and the prominences and solar corona that extend beyond the disk, which are normally invisible due to the intense brightness, become visible for a few brief minutes.