In an eclipse of the Sun, the point when the Moon’s disc first begins to move across the Sun’s photosphere. In a lunar eclipse, first contact occurs when the Moon enters the full shadow umbra of the Earth. The term may also be used to describe the similar stage in the progress of a transit or occultation. Also a somewhat theoretical term for humans meeting extraterrestrial intelligence for the first time, largely promoted by science fiction novels and movies but whose use is innevitable should the occasion arise.