The first and foremost reason for why all planets move around the sun is that sun has very strong gravitational force which makes the planets to move around it Just as the moon revolves around the earth because of earth’s gravitational force. So here the question arises that if it is due to gravity then why do planets have an elliptical orbit? As the pull must be same throughout the rotation of planets or they should completely move towards the sun rather than revolving. This happens because earth velocity’s direction makes the angle of 90 degree to the force of sun’s pull. Earth would start moving in a straight line if there will be no sun. This is the gravity of the sun which makes the earth and other planets to revolve around it.
This can be better understood with example. Let us suppose a man with supernatural powers is standing on Mt. Everest and he throws the ball up with great speed because it is thrown by the man with great powers so it passes the horizon before coming back. We know that our earth is curved so it keeps on moving and continuously “falling†but will not reach the earth because the ball has reached in the atmosphere, the earth has curved surface and the part from where the ball has been thrown will move away. This is the process how the planets move in an orbit.
Always a force is required to move an object, to stop it or to change its direction. Planets does fly off in the space but they revolve around the sun because of sun’s strong gravitational force.
I have read so many people telling that planets revolve around the Sun due Sun’s gravity. Gravity is a force of attraction and is something that draws towards itself. Therefore all planets should come towards the Sun. But we all know that there is tangential movement around the Sun and also each planet rotates around its own axis. Force of gravity of Sun cannot cause revolution and rotation of planets. I feel ascribing all movement of planets – both revolution and rotation to Sun’s gravity is wrong. I feel that there is some other force which causes these two movements and I can give answers to both through my imagination if you wish. I will give my answers after hearing from you.