According to Britannica, the fall equinox is one of two moments in the year when the sun is exactly above the equator. The celestial event happens annually around Sept. 22 or Sept. 23 in the Northern Hemisphere and on March 19 or March 20 in the Southern Hemisphere.

The sun's light and warmth fall unequally on the northern and southern halves of the planet, so during different seasons, the Northern Hemisphere is tilted toward or away from the sun, meaning the temperatures and daylight wax and wane.

The autumnal equinox brings fall to the Northern Hemisphere today as the sun passes directly over the equator at noon. But are day and night actually equal length today?