Energy and momentum

Energy

Kinetic energy is the energy associated with the motion of an object. Stars, planets and galaxies generally possess kinetic energy, due to their motion though space (translational kinetic energy) and their rotation (rotational kinetic energy). There are other kinds of energy.

Gravitational energy is acquired by a mass by virtue of its position within a gravitational field. Gravitational energy is involved in the initial stages of star formation, as the star contracts. 

Electromagnetic energy is the energy associated with electric and magnetic fields. An electromagnetic wave, such as light, carries with it radiant energy. 

Chemical energy is released in chemical reactions. It is ultimately derived from the kinetic and electromagnetic energy of atoms and molecules. 

In nuclear reactions, we have nuclear energy. This is the source of power for the Sun and other stable stars. 

Internal/thermal energy is due to the kinetic energy of the molecules within the thing. The electromagnetic forces acting between them also works towards this internal energy. 

Momentum

Momentum is a quantity associated with the motion of an object. The momentum of an object is the product of its mass and velocity. It should be noted that force, is the rate of change of the momentum. 

Momentum should not be confused with kinetic energy. Both depend on mass and speed, yet, momentum is a vector. The direction of said vector is the direction of velocity. Kinetic energy has no direction associated with it. 

Objects that rotate on their axis (a star or planet) possess angular momentum. This is momentum analogous to the linear movement of an object in a straight line. Angular momentum is a vector.