Where are the nights and days equal on earth?

There are two days out of the whole year when day and night are just about the same length: 12 hours. These days are called equinoxes because the direct sunlight rays move toward the equator, making the sunlight about equal in both the Northern and Southern Hemispheres. The Fall (autumnal) equinox for the Northern Hemisphere is September 21 or 22, and the Spring Equinox is March 20. In the Southern Hemisphere, the names are reversed for the two days.

Because of the apparent width of the solar disc, the days at the equinoxes are still slightly longer than the night. The parity of day and night occurs the day before the vernal equinox, and the day after the autumnal equinox.