Pumpkin spice, cooler nights, football weekends and clock changes: fall is on the horizon. But the official start of autumn isn’t about lattes or leaf piles. It comes down to astronomy. The autumn ...

As the earth spins on its axis, producing night and day, it also moves about the sun in an elliptical (elongated circle) orbit that requires about 365 1/4 days to complete. The earth's spin axis is ...

The Earth orbits the Sun once every year, but it doesn’t spin upright. Instead, it’s tilted on its axis by about 23.5 degrees. This tilt is the reason we have seasons. As the Earth moves around the ...