What is the size of the gravitational force acting on the earth due to the sun?

Consider the earth following its nearly circular orbit about the sun. The earth has mass earth = 5.9810^24 kg and the sun has mass sun = 1.9910^30 kg. They are separated, center to center, by r = 93 million miles = 150 million km.

1 Answer
Jan 31, 2016

Answer:

Zero.

Explanation:

There is no such thing as a gravitational force. Newton described gravity in terms of a force. It is however just a good approximation.

Einstein's general theory of relativity describes gravity as curvature of 4 dimensional spacetime. The Sun's mass curves spacetime. The Earth has no force acting on it from the Sun. It travels along a geodesic which is the spacetime extension of a straight line.

The Earth appears to have an elliptical orbit but it is in fact the projection of the 4 dimensional geodesic onto our familiar 3 dimensions.