The shape of Earth's orbit becomes more or less oval, Earth wobbles as it spins, and Earth's axis changes too. All these changes, over thousands of years, causes Earth's climate to change.
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Windows to the Universe

How the Sun Affects Climate: Solar and Milankovitch Cycles

Energy from the Sun keeps Earth nice and warm. Sometimes Earth doesn't get as much energy from the Sun. This happens either when the Sun is not as warm or when the Earth's orbit changes.

Sometimes the Sun Changes!
When the Sun has fewer sunspots, it gives off less energy. That means that less energy makes its way to Earth, and our planet cools down. Over time, scientists have noticed a pattern in the number of sunspots. About every 11 years the number of sunspots reaches a high and then decreases again.

Sometimes the Earth's Orbit Changes!
Over thousands of years, changes in Earth's orbit cause changes in the amount of the Sun's energy that can get to the planet. These changes cause global warming and cooling.

There are three ways that Earth's orbit changes over time.

  • The shape of Earth's orbit around the Sun can become slightly more and then less oval.
  • Earth wobbles as it spins.
  • The angle of the Earth's axis, its tilt, changes.

Once the Sun's energy reaches the Earth, several things can happen. The energy can be absorbed by the planet, reflected back into space, or become trapped in the atmosphere.

Last modified April 16, 2008 by Jennifer Bergman.

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