Ok.Astronuc said:When posting, please use proper English.
Planets revolve around much more massive stars. The gravity keeps them from leaving, and the centripetal force of their motion balances the force of gravity, so the planets maintain an orbit. Satellites and spacecraft in orbit around the earth, and the moon orbiting the Earth experience the same process.
In order for a satellite or spacecraft to remain in orbit, it must be traveling at orbital velocity.
Please refer to - http://hyperphysics.phy-astr.gsu.edu/hbase/corf.html#cent
http://hyperphysics.phy-astr.gsu.edu/hbase/orbv.html#co
Nick89 said:You can see an orbiting body (let's say a satellite around the earth, but the same applies to the Earth around the sun) as a body that is continuously falling toward the earth, but it just keeps missing it!
There's a well known picture (although I can't find it now) where a bullet or projectile is fired from a (greatly exaggerated) high tower. If the projectile is relatively slow, it simply falls to the ground. When it gets faster and faster however, its trajectory will 'bend' around the curvature of the Earth more and more. Eventually, it will get back to the position where it started, having completed one orbit.
Gravitational force is an attractive force that exists between all objects with mass. The force is strongest between objects with larger masses and decreases as the distance between the objects increases. This force is what keeps planets in orbit around the sun and prevents them from colliding with each other.
The gravitational force between the sun and planets is balanced by the planets' inertia, which is the tendency of an object to resist changes in its motion. As the planets orbit the sun, they are constantly moving forward, preventing them from being pulled into the sun by its strong gravitational force.
Other factors that contribute to the stability of planetary orbits include the speed of the planets, the shape of their orbits, and the presence of other objects in the solar system. These factors, along with the gravitational force, work together to keep the planets in stable orbits around the sun.
Yes, gravitational force can affect the shape of a planet's orbit. For example, the gravitational pull of other planets can cause slight changes in a planet's orbit, leading to an elliptical or non-circular shape. However, these changes are usually small and do not significantly impact the stability of the orbit.
Yes, there is a limit to how close planets can get to each other without colliding. This distance is known as the Roche limit and is determined by the mass and size of the planets, as well as their distance from each other. If two planets get too close, the gravitational force between them can overcome their structural integrity, causing them to collide or break apart.