So long, summer. The first day of fall, also known as the autumnal equinox, is Sept. 23. It’s when the sun crosses the celestial equator from the north to the south.
Fall is caused by the tilt of the earth and not the distance from the sun. This is the time of year when the nights will get longer and the days will get shorter. Leaves change color due to the amount of daylight and photosynthesis, not because of the weather, as most people believe.
“Autumn days come quickly, like the running of a hound on the moor.” – Irish proverb.