Understanding Earth's Seasonal Changes

The exact dates of seasons are determined by Earth's tilt and position relative to the sun,

not random calendar picks. Winter solstice marks the shortest day,

happening December 21 in the Northern Hemisphere but June 20 in the Southern Hemisphere.

Summer solstice brings the longest day, while spring and fall equinoxes have

equal daylight and darkness. This happens because Earth tilts on its axis as it orbits

the sun. When your hemisphere tilts toward the sun, you get summer.

Tilt away, you get winter. That's why Australia experiences winter in June while North

America bakes in summer heat.