What is an eclipse? An eclipse occurs when one celestial body passes in front of another and obscures it. On Earth we get two kinds of eclipses. There are solar eclipses, which happen when the Moon passes in front of the Sun. There are also lunar eclipses, which happen when Earth passes between the Sun and the Moon. Solar eclipses come in three varieties: partial, when the Moon covers only some of the Sun; total, when the Moon covers the Sun completely; and annular, when the Moon is near its farthest point from Earth and thus covers only the center ...(100 of 505 words) Access the full article Help support true facts by becoming a member. Subscribe today!