Happy #FirstDayOfFall to those in the Northern Hemisphere! Do you know what causes the seasons? It's all about Earth's tilt. Learn more at @NASASpacePlace:
The equinox happens twice a year in our year-long trip around the Sun. In the Northern Hemisphere, it's the #FirstDayofFall. In the Southern Hemisphere, spring is here!
More:
🍂Fall is here!🍂
The #AutumnalEquinox, when daytime and nighttime are both 12 hours, marks the first day of the season! Enjoy the colors! #FirstDayOfFall