Solar eclipse. Montage image of the sun (white) during a solar eclipse. The black shapes show the varying position of the moon at it passed in front of the sun, from top left to bottom right. At totality the moon would have fitted completely over the sun and only the sun's corona (atmosphere) would have have been 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.