In Ptolemy's earth-centered model for the
solar system, Venus's phase is never full as viewed from earth because it
always lies between earth and the sun. In reality, as Galileo first recognized,
Venus is full.
<span>Venus is closer to the Sun than Earth. That
is why we cannot see the full Venus. However, Venus is full (whenever it is on the opposite side
of the Sun from Earth). From Earth, Venus's phases range only between new and
crescent.</span>
