# Rotation of the Earth about its own axis [duplicate]

I am wondering how the Earth got its original angular velocity. What was the cause that made the Earth rotate about its own axis?

What about its motion around the Sun? What gave the Earth the push to keep rotating around the Sun?

There are two main phenomena that explain Earth rotation. First one is linked to the history of the solar system: there is angular momentum in the interstellar medium (ISM), so the collapsing cloud that formed our solar system had an initial angular momentum (rotation of the galaxy and turbulence in the ISM are typically a good candidate for that; see for example Mac Low & Klessen 2004). By conservation of the latter, particles in the collapsing cloud accelerate (the norm of the angular momentum $$I$$ is $$mrv$$, with $$m$$ the mass of the system, $$r$$ the radius and $$v$$ the velocity; as the cloud contracts, $$r$$ decreases and then $$v$$ has to increase) and due to centrifugal force, a disk will tend to form. By conservation of the angular momentum in the protoplanetary disk, you will also tend to form bodies that rotates.