A centripetal force (from Latin centrum "center" and petere "to seek") is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path. Isaac Newton described it as "a force by which bodies are drawn or impelled, or in any way tend, towards a point as to a centre." In Newtonian mechanics, gravity provides the centripetal force responsible for astronomical orbits.