Does the Earth rotate since the materials it was made of were spinning?

1 Answer
Mar 29, 2016

Essentially, yes the Earth retains the initial spin that the entire solar system had during its formation, plus it picked up additional momentum during the collision with a large proto-planet.


According to the Nebular Hypothesis, the solar system formed from a swirling cloud of nebulae materials. This gave the sun and planets their initial movement - called initial angular momentum. Earth rotates in counter-clockwise fashion when looking down. So does the sun and most other planets. Once a body gets spinning in the vacuum of space, there isn't much to slow it down except for some solar winds.

The Earth got a second kick when a large Mars sized proto-planet hit the early Earth. Somewhat by chance, this additional kick re-enforeced the same direction the Earth had been spinning anyway. Not so with the planet Venus, who's orbit spins backwards to the other planets in the solar system. Venus may also have been hit by a large porto-planet as the solar system was forming, but this caused it to spin backwards from everyone else!