When I was talking about balancing a stick, I mentioned the moment of inertia. Moment of inertia is different than mass, but I like to call it the “rotational mass”. What does mass do? Things with ...

The rotation of stars in galaxies such as our Milky Way is puzzling. The orbital speeds of stars should decrease with their distance from the center of the galaxy, but in fact they all have the same ...

A new rotation curve analysis of the Milky Way reveals that conventional axisymmetric mass models cannot fully reconcile both photometric profiles and observed stellar motions. By modeling stellar, ...

Astronomers discover that the rotation speeds of distant planets reveal how they form and evolve in the universe ...