Total solar eclipse. Montage image of the sun (white) during a total solar eclipse. The black shapes show the varying position of the moon at it passes in front of the sun, from left to right, and blocks out the sun's light (bright spot). At totality (far right) the moon fits completely over the sun and only the sun's corona (atmosphere, white disc) is visible. The moment of totality lasts for only a few minutes. Total solar eclipses usually occur less than once a year and can only be seen from a small area of the Earth's surface.