1. Gravity: The Sun's immense mass creates a powerful gravitational field. This field pulls on everything around it, including the planets. The Sun's gravity is what keeps the planets from flying off into space.
2. Initial Motion: When the solar system was forming, the cloud of gas and dust from which it originated was already spinning. As the cloud collapsed under its own gravity, the spinning motion intensified. This initial spin gave the planets their initial sideways motion, which is essential for their orbits.
The Combined Effect:
Imagine throwing a ball horizontally. It will travel a certain distance before gravity pulls it back down. Now imagine throwing the ball much faster. It will travel further before falling back down.
If you could throw the ball fast enough, it would travel in a circle around the Earth. This is because the Earth's gravity is constantly pulling the ball towards the center, but the ball's forward motion keeps it from falling straight down.
Planets are like the ball, traveling at a high enough speed that their sideways motion constantly counteracts the Sun's pull, resulting in a stable orbit.
Important Note: Planets don't actually revolve in perfect circles around the Sun. Their orbits are slightly elliptical, meaning they are slightly oval-shaped.
