What causes a solar eclipse to happen?

A solar eclipse occurs when the Moon passes directly between the Earth and the Sun, casting a shadow on Earth's surface. This alignment blocks sunlight from reaching certain areas of Earth, either partially or completely. A total solar eclipse happens when the Moon fully covers the Sun's disk, which is possible because although the Sun is about 400 times larger than the Moon, it is also roughly 400 times farther away, making them appear nearly the same size in the sky. Solar eclipses only occur during a new moon phase, but not every new moon causes an eclipse because the Moon's orbit is tilted about 5 degrees relative to Earth's orbit around the Sun, so perfect alignment is relatively rare.