The Earth's rotation around the sun determines the seasons. Seasons in the Northern Hemisphere are the opposite in the Southern Hemisphere. Equinoxes occur when parts of the Earth experience equal amounts of daylight and dark—in the spring and fall. Solstices occur on days experiencing the most sunlight (summer solstice) and the least sunlight (winter solstice).

Illustration by Tim Gunther

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The Reason for the Seasons
The Reason for the Seasons Activity

Best For
2 - 5

Mathematics, Science, Informal Education

Appropriate For

  • Educators
  • Families

Students use polystyrene foam balls and light bulbs to investigate the sun's intensity on the surface of the Earth.