What causes the seasons?

The seasons are primarily caused by the tilt of the Earth's axis as it orbits the Sun, not by our distance from the Sun.

Here is how it works:

• The Tilt: The Earth rotates on an axis that is tilted at an angle of about 23.5 degrees relative to its path around the Sun. Because of this tilt, the Earth does not stand straight up and down in space.
• Varying Sunlight: As the Earth travels in its orbit, this tilt causes different parts of the planet to receive varying amounts of direct sunlight throughout the year:
  • Summer: When a hemisphere is tilted toward the Sun, it receives more direct, concentrated sunlight for a longer period each day. This causes temperatures to rise.
  • Winter: When a hemisphere is tilted away from the Sun, the sunlight hits the surface at a shallower angle and for a shorter duration each day. This results in less heating, leading to cooler temperatures.
• The Seasonal Cycle: Because of this consistent tilt, the Northern and Southern Hemispheres experience opposite seasons. When the North Pole is tilted toward the Sun, the Northern Hemisphere experiences summer, while the Southern Hemisphere, tilted away, experiences winter. Six months later, the positions are reversed as the Earth moves to the other side of its orbit.

The equinoxes mark the two points in the orbit where the tilt is not oriented toward or away from the Sun, resulting in nearly equal day and night lengths globally.