How does Earth, or any other celestial body, keep spinning indefinitely?
In: Physics
Basically there is very little to stop it, the spin continues until there is a large enough force to slow it down and stop it, while the Earth is very slowly changing the Sun will swallow the Earth before anything significant happens.
If you make a ball spin on the tip of your finger inside of your room it will not spin for ever because there are forces that will make it stop. Like the air around it or the friction against your finger. Earth spinning does not have air around or finger that cause friction but (how they told you above) it has tides that will make it stop eventually (it will take a LONG time)
The Earth’s spin is, in fact, slowing down… slowly, due to tidal effects, which in turn are down to gravity. But basically you’re looking at Newton’s First Law of Motion which states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. There are no external forces acting upon the earth, other than gravity (which cause it to rotate about the sun – a “straight line” in the geometry of the curved space it finds itself in, thank you gravity and Einstein) so it just carries on going [edit] and spinning… (well, I guess there are forces such as the solar wind, but they’re pretty negligable in this context.)
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