sentences:  For an eclipse to occur, either the Moon must be located between the Earth and Sun (for a solar eclipse) or the Earth must be located between the Sun and Moon (for a lunar eclipse).This can happen only when the Moon is new or full, respectively, and repeat occurrences of these lunar phases result from solar and lunar orbits producing the Moon's "synodic period" of 29.53059 days.During most full and new moons, however, the shadow of the Earth or Moon falls to the north or south of the other body.