Equinox

An equinox occurs twice a year when the Sun is directly above the Earth's equator, resulting in nearly equal daylight and nighttime hours worldwide. This happens around March 20th (vernal or spring equinox) and September 23rd (autumnal or fall equinox). During an equinox, the tilt of Earth's axis is such that it's not inclined away from or toward the Sun, causing day and night to be approximately equal in length. Equinoxes mark the change of seasons and are important for calendars and timekeeping, reflecting Earth's consistent orbit and axial tilt relative to the Sun.