Expert: Jayendra Upadhye - 12/20/2005

Question
What are the forces that keep satilites in orbit around their planets and planets (along with their satilites) in orbit around the sun?

Answer
Hi,
Hey the force that keeps all the planets orbitting around the sun and satellites around planets is nothing but gravitational force.
    all objects around you fall downwards only and instead
do not go upwards only because of gravitational force.
it was discovered by Sir Issac Newton.
    according to newtons law any two bodies in the universe attract each other with a force directly proportional  to  the product of their masses and divided by the square of the distance seperating them as per inverse square law.here the constant of proportionality G
which is called universal constant of gravitation was evaluated by cavendish around 1905 (plz check for year)
 
hope this suffices.
Jayen