NASHVILLE, Tenn. (WSMV) – Fall is upon us and that means there will be more darkness than daylight in the days leading up to the first day of winter.

The amount of daylight we see in a 24-hour period depends entirely on the position of the sun relative to the Earth's equator. Twice a year, around March 20 or 21 and September 22 or 23, the sun's rays shine directly over the equator. In the Northern Hemisphere, these times are known as the spring equinox and the autumn equinox.

Instead of tilting away from or toward the sun, during the equinox the Earth's axis of rotation is perpendicular to the line connecting the centers of the Earth and the Sun. Because of this, we have almost exactly equal amounts of time in day and night. Daytimes are so balanced around the world during the equinox that there are almost 12 hours of daylight and 12 hours of darkness.

From that point on, daylight in the Northern Hemisphere will gradually get shorter until the winter solstice on December 21, 2024. This is because the Earth in the Northern Hemisphere is currently tilting away from the Sun. The winter solstice is known as the shortest day of the year.

This year, the first official day of fall is Sunday, September 22nd at 7:43 a.m. CT.

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