Equinox is when the Earth's axis of rotation is perpendicular to the path from Earth to Sun. That is, when the poles are neither tilting "towards" the Sun (whi

Equinox is when the Earth's axis of rotation is perpendicular to the path from Earth to Sun. That is, when the poles are neither tilting "towards" the Sun (which happens in summer) nor "away" from the sun (which happens in winter).