The start of fall in the Northern Hemisphere is driven primarily by the tilt of Earth’s axis, which is about 23.5 degrees. As Earth orbits the sun, this tilt causes different seasons:
- Summer: When the Northern Hemisphere tilts toward the sun.
- Winter: When it tilts away from the sun.
- Spring and Fall: When neither hemisphere tilts toward or away from the sun.
The autumn equinox, which occurred recently, is when the sun crosses the equator and begins its journey southward. This results in shorter days and cooler temperatures in regions like Central Illinois, as the sun’s position is lower in the sky, leading to less solar heating.
A common misconception is that the distance between the Earth and the sun affects the seasons. In reality, Earth is closest to the sun during winter (perihelion in January) and farthest during summer (aphelion). Consequently, while the Northern Hemisphere experiences fall and winter, the Southern Hemisphere enjoys its warmer seasons.
Enjoy the beauty of fall with its changing colors and cooler days!
