What you should know about the autumn equinox

The leaves are changing, pumpkin-flavored food is back, and football is on TV. Fall is back, baby!

The official first day of fall, also known as the autumnal equinox, is this weekend in the Northern Hemisphere. According to the Encyclopedia Britannica, it's one of only two days. The other is the spring equinox, when the sun is directly over the equator, essentially dividing day and night into equal sections.

“On any other day of the year, either the Northern or Southern Hemisphere is tilted toward the sun because the Earth's axis is tilted 23.4 degrees,” says Britannica. This means that one hemisphere receives more sunlight than the other.