2 added 4 characters in body edited May 5 '16 at 18:20 ahemmetter 3,28433 gold badges2222 silver badges4040 bronze badges In an isotropic space (which means it's equal in all directions), Noether's theorem tells us that angular momentum is conserved. For the Earth this means that it keeps it'sthe angular momentum that it has now. This can be calculated from $$L = I \omega$$ where $$I$$ is the moment of inertia and $$\omega$$ the angular speed. You'll see that if $$L$$ remains constant (and $$I$$ of course too, since it only depends on the distribution of mass in the body), also $$\omega$$ will stay constant. That means that in effect, Earth won't stop spinning. To change the angular momentum you need to apply a torque, for example from a (non-frontal) collision with another object. $$M = \dot{L}$$ In an isotropic space (which means it's equal in all directions), Noether's theorem tells us that angular momentum is conserved. For the Earth this means that it keeps it's angular momentum that it has now. This can be calculated from $$L = I \omega$$ where $$I$$ is the moment of inertia and $$\omega$$ the angular speed. You'll see that if $$L$$ remains constant (and $$I$$ of course too, since it only depends on the distribution of mass in the body), also $$\omega$$ will stay constant. That means that in effect, Earth won't stop spinning. To change the angular momentum you need to apply a torque, for example from a (non-frontal) collision with another object. $$M = \dot{L}$$ In an isotropic space (which means it's equal in all directions), Noether's theorem tells us that angular momentum is conserved. For the Earth this means that it keeps the angular momentum that it has now. This can be calculated from $$L = I \omega$$ where $$I$$ is the moment of inertia and $$\omega$$ the angular speed. You'll see that if $$L$$ remains constant (and $$I$$ of course too, since it only depends on the distribution of mass in the body), also $$\omega$$ will stay constant. That means that in effect, Earth won't stop spinning. To change the angular momentum you need to apply a torque, for example from a (non-frontal) collision with another object. $$M = \dot{L}$$ 1 answered May 5 '16 at 12:16 ahemmetter 3,28433 gold badges2222 silver badges4040 bronze badges In an isotropic space (which means it's equal in all directions), Noether's theorem tells us that angular momentum is conserved. For the Earth this means that it keeps it's angular momentum that it has now. This can be calculated from $$L = I \omega$$ where $$I$$ is the moment of inertia and $$\omega$$ the angular speed. You'll see that if $$L$$ remains constant (and $$I$$ of course too, since it only depends on the distribution of mass in the body), also $$\omega$$ will stay constant. That means that in effect, Earth won't stop spinning. To change the angular momentum you need to apply a torque, for example from a (non-frontal) collision with another object. $$M = \dot{L}$$