Fall equinox - First day of fall
Sep 23, 2019
Autumn equinox! Fall begins in the Northern Hemisphere. The sun is overhead at the equator in its apparent journey south. Days and nights are equal, 12 hours of daylight and 12 hours of darkness everywhere on the globe.
As the United States tilts away from the sun, the sun's arc appears lower in the sky. Rays hit us less directly, and the top half of the globe cools off. All living things compensate for the reduced energy!
The sun's rays hit the earth broadside on the first day of fall and on the first day of spring.
The sun is out to our side, not overhead. We can see this by lying on the ground with our heads pointing north. The earth spins, turns & rotates from west to east as the sun appears to cross our sky. The sky result from our atmosphere scattering the sun's rays.
The earth tilts as it travels. On the first day of fall, we are in that part of its orbit where days and nights are equal. 3 more months, and we will be in that part of its orbit where the United States tilts away from the sun.
Earth's tilt causes the seasons. That we are closest to the sun in January and fartherest from the sun in July helps to moderate the seasons.
Time - The earth rotates from west to east, which means the sun is high in Louisville and Nashville before it is high in Las Vegas. Time is adjusted so that when it is 12 noon in Nashville, it is 10am in Vegas. There are 3 hours difference in our time zones: Eastern, Central, Mountain & Pacific.
Astronomer Bob Berman compared the Earth rotating while revolving to patting our heads while rubbing our stomachs.