As the moon travels around the earth, it passes between the earth and the sun once each month.
The orbit of the moon around the earth is not in a direct line with the earth’s orbit around the sun, so the moon usually doesn’t pass directly in front of the sun. But when it does, it blocks out part or all of the sun, and this event is known as a solar eclipse.
Sometimes, the moon covers only part of the disk of the sun. This is a partial eclipse. Other times, it covers almost all the sun’s disk, except for a ring, or annulus, around the edge of the sun. This is an annualar eclipse. When the moon completely covers the disk of the sun, a total eclipse occurs.
In ancient times, the darkening of the sun during an eclipse caused great fear among people, and was often thought to show the anger of the gods.
There are at least two solar eclipses each year, but an eclipse can be seen from only part of the earth. The greatest number of solar eclipses possible in a year is five. And the longest a solar eclipse can last is 71/2 minutes!