Many notice summer's transition to fall when the night air turns crisp or when department stores showcase their displays of pumpkins, gourds and brightly colored leaves.
But fall officially starts today.
This year's autumnal equinox occurs today at 12:30 p.m., according to the U.S. Naval Observatory. The sun will rise at 6:16 a.m. and set at 6:24 p.m.
According to the Naval Observatory, the vernal and autumnal equinoxes occur each year in spring and fall when the sun crosses the celestial equator.
During the spring and autumnal equinoxes, day and night are split equally, said Dr. Tom Crute, an associate professor at Augusta State University's Chemistry and Physics Department.
In the summer, the sun is positioned higher in the sky than it is during the winter, Dr. Crute said. But during the equinox, the position of the sun sits half-way between these two points, exactly over the earth's equator, he said.
"This is sort of a crossover point, if you will," Dr. Crute said. "It's kind of a calling that fall is coming. The seasons occur because of the angle of the sun."
You don't need to be an astronomer to notice the equinox is here.
For the past week, Dr. Crute has been painfully aware of the sun's changing position.
As the equinox approaches and the sun dips lower in the sky, the blinding rays stream through a window in his home, preventing him from eating supper at his kitchen table.
And anyone driving down Wrightsboro Road, or another street running due west or east, might have experienced difficulty driving as the sun sets or rises, Dr. Crute said.
"The road runs very closely east-west," he said. "On equinox days, the sun sets right over the road. Every other day, it's to the north or south of it."
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