Planets in our solar system are held in their fixed revolutions by

Question

isaiah.feynman · Answer

The warping of space time due to the mass of the sun (Einsteinian definition). 
The centripetal force on the planets due to the circular path they take. This force is gravity. (Newtonian definition).

anonymous · Answer

Isaiah means the _eliptical_ path they take in the Newtonian definition.

mrnood · Answer

The force is not due to the path.

In Newtonian terms a body will continue to travel in a straight line unless acted upon by a force.

The path is due to the force.

As ghuczek says - these orbits are elliptical not circular but the eccentricity of the Earth's orbit is currently about 0.0167; the Earth's orbit is nearly circular.