Final answer:
The Autumnal Equinox occurs around September 21st each year and marks the transition from summer to fall. During this equinox, there are approximately 12 hours of daylight and 12 hours of darkness.
Step-by-step explanation:
The Autumnal Equinox occurs around September 21st each year. It is a time when the Sun crosses the celestial equator, appearing directly above Earth's equator. During this equinox, every place on Earth experiences approximately 12 hours of daylight and 12 hours of darkness. The Autumnal Equinox marks the transition from summer to fall.