Which equinox marks the transition from summer to fall?

• A. March Equinox
• B. June Solstice
• C. September Equinox
• D. December Solstice

Answer: (C)

The September Equinox, also known as the Autumnal Equinox, marks the transition from summer to fall in the Northern Hemisphere. This event occurs around September 22nd or 23rd, when the sun crosses the celestial equator, resulting in nearly equal lengths of day and night. During this time, the sun's position shifts, leading to cooler temperatures and the gradual onset of autumn. It signifies the beginning of fall, as the days become shorter and temperatures continue to decline until winter arrives.

Other options refer to different seasonal transitions: the March Equinox signals the start of spring, the June Solstice marks the beginning of summer, and the December Solstice indicates the start of winter. Each of these points represents a significant change in the annual cycle related to the sun's path and its impact on weather and daylight hours.