Hi pf, please could someone explain why the orbital velocity increases as you get closer to the sun. I treated the situation like circular motion and did a load of calculations. I calculated the orbital velocity of all 8 planets and then the force between each of the eight planets and the sun. I thought the force would drop off as you for further away which would explain the slower orbital velocity but that isn't the case. For instance, Jupiter is 5 times further away than Earth, has a much slower orbital velocity but has a stronger gravitational pull from the Sun. The only thing I can think of is dividing out the mass of the planet. So although Jupiter has a greater gravitational force (despite orbiting slower) it is much more massive so will require a bigger force even to orbit at this slower speed. Or to put it another way if all 8 planets had the same mass as each other then the force would decrease for all planets with increasing distance. Is that right?