Autumnal Equinox

The Autumnal Equinox will occur on Tuesday, September 22, 2026, at 8:06 pm EDT. It is the time of year when an imaginary plane would pass through both Earth's Equator and the Sun's center. At this auspicious moment, the number of sunlight hours and nighttime hours are about the same over much of the Earth. 

This activity has been updated to have 3 parts:

• A chart observation of daylight hours (Grades 5-8)
• A comparison of daylight patterns across three latitudes (Grades 6-8)

• A sinusoidal modelling activity where students find the equation that fits the data, suitable for Grades 9+