L occultare frequent.
Occultations occur when one celestial object passes in front of another celestial object.
For example, when the Moon passes in front of a background star, light from the background star is prevented from reaching the Earth. A shadow of the Moon is cast by the star onto the Earth, and this shadow sweeps across the Earth at roughly the same speed as the Moon is moving. A special case of an occultation is a Total Solar Eclipse , in which the Moon passes in front of the Sun, obscuring it from view. Many important discoveries have been made in this way. Total Lunar Occultations occur when the Moon passes in front of background stars.