Why does the earth revolves* around the sun?
There are two balancing forces acting on earth when it revolves around the sun.
Gravitational force of attraction.
Law of Universal Gravity states that every body in this universe attracts every other body with a force which is called force of gravity. The force
It has the value
In our case, one is the sun and other earth.
Centrifugal force is a 'fictitious' force that appears to act on all rotating objects and is directed away from the axis of rotation.
It is given by the expression
These two forces balance each other and keep the sun-earth system in equilibrium.
*in the question 'revolves' is preferred word as earth 'rotates' around its axis.