What is an Eclipse?
A solar eclipse occurs when the Moon passes between the Earth and the Sun and the Moon blocks the Sun for a viewer on Earth. During a total eclipse, the Moon lines up perfectly to fully obscure the Sun, resulting in "totality"; in a partial eclipse, the Moon and the Sun are not perfectly aligned and only part of the Sun is blocked; and during an annular eclipse, alignment is perfect but the Moon is too far away from the Earth to completely obscure the Sun. Due to the peculiarities of the Moon's orbit, no more than five solar eclipses can occur in any given year, and no more than two can be total. This, in addition to the fact that a total solar eclipse is visible on the Earth's surface only along a very narrow path for just a few short minutes, makes totality one of nature's rarest events.