I know earth rotates around itself and the sun but what makes it rotate? (Sory for my english not my native language).
In: Earth Science
An object in motion tends to stay in motion (Newton’s First Law of Motion). There is no significant friction or drag in space to slow it down and so adding energy is not required. In fact, energy would need to be used for it to slow down.
The Earth’s motion is leftover from from the motion of the cloud of matter that formed the solar system. That cloud condensed into the sun and planets due to gravity. The relatively high speed of Earth’s rotation (both around itself and around the sun) is a result of that process.
This is described by the conservation of angular momentum, where matter rotating slowly when spread out will rotate more quickly when it is condensed. A common demonstration of this is a spinning figure skater whose rotation speed increases or decreases as they move their arms inward or outward.
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