There are only two times of the year when the Earth's axis is tilted neither toward nor away from the sun, resulting in a "nearly" equal amount of daylight and darkness at all latitudes. These events are referred to as Equinoxes. The word equinox is derived from two Latin words - aequus (equal) and nox (night).

The equinoxes happen in March (about March 21) and September (about September 23). These are the days when the Sun is exactly above the Equator, which makes day and night of equal length.

The start of astronomical spring, known as the vernal equinox, occurred yesterday, March 19, 2024, at 11:06 p.m. EDT. During equinoxes, which happen twice a year, the Earth's axis is not tilted toward or away from the sun, resulting in nearly equal periods of daylight and darkness worldwide.