Fall equinox occurs Tuesday, marking equal day and night

The fall equinox fell on Tuesday, September 23, when the sun crosses the celestial equator and the length of daylight and darkness becomes nearly equal. Astronomers note that the event marks a precise point in the Earth’s orbit where the planet’s axial tilt is neither inclined toward nor away from the Sun, producing the balanced day and night that define the equinox.

For the Northern Hemisphere, the equinox signals the official start of autumn, bringing cooler temperatures, shorter days, and the first changes in foliage. In the Southern Hemisphere, the same astronomical alignment heralds the beginning of spring, with increasing daylight and the return of warmer weather. The equal division of light and dark has been observed for millennia and is used by cultures worldwide to schedule agricultural activities, festivals, and seasonal rituals.

The equinox’s predictable timing provides a reliable reference for scientists and planners alike. By marking the transition between seasons, it helps coordinate everything from planting calendars to energy consumption patterns, underscoring its continued relevance in modern society.