Why do the planets revolve around the sun?

Answer

A planet like our own Earth would actually prefer to keep moving straight ahead. That’s just how it is in physics: bodies will simply move in a straight line unless there is a force acting on them that deflects the motion. In the case of a planet, that force is the attraction between the sun and the planet. This causes the planet to deflect its motion.

You can simulate it yourself as follows (outside in the garden, and far away from all windows!). You attach a weight to a rope and swing around. You are then the sun, and that weight is the planet. The rope is the pull of the sun. Just as that weight cannot move away from you through the rope, and continues to move in a circle, the planet will not be able to move away from the sun, and will continue to move in (almost) a circle.

What would happen if the gravitational pull of the sun suddenly disappeared? Watch what happens when you let go of the rope: the weight would fly off in a straight line. Well, Earth or any other planet would do the same if the sun suddenly disappeared.

But as long as the sun is there, it will force the planets to orbit around it, by means of gravity.