There are two equinoxes every year: one in March and one in September. In September, the Sun crosses the equator from north to south. Sun Crosses Celestial Equator The September equinox is the moment the Sun crosses the celestial equator—an […]

December Solstice: Longest and Shortest Day of the Year There are two solstices every year: one in December and one in June. The December solstice marks the shortest day north of the equator and the longest day in the south. Sun Reaches Most […]