Combined gravitational forces from earth and sun keep them in homeostasis.
Edit: Each planet has its own orbit and they are well separated. The planets
do affect each other a bit, but their orbits are very stable. In fact Neptune was discovered because of its small effect on the orbit of Uranus.
Billions of years ago when the solar system was forming there probably were collisions, but it shouldn't happen now.
Without the planets orbiting the sun all the planets would be cold and dark
The other planets - and all other bodies - orbit the earth.
All the planets in OUR solar system orbit around the sun(which is a star). Planets in other solar systems orbit around other stars.
Pluto's orbit is longer and slower than other planets.
Moons orbit planets. Planets orbit stars. Some stars orbit other stars, or orbit their mutual center of gravity. Stars orbit the center of the galaxy. Galaxies may orbit the center of the "galactic group".
Not all the planets orbit the sun - other stars have planets too. But all the planets in our solar system, which is the system of our sun, revolve around the sun; otherwise they would be in other solar systems. All the planets we can see with our naked eye orbit the sun, since the planets orbiting the sun are the only ones close enough to earth to see without a telescope.
Extra solar (or Exo) planets are planets that do not orbit the Sun. Planets in our solar system orbit the Sun.
In fact, Venus, Uranus, and the "dwarf planet" Pluto orbit the Sun in the same direction as all the other planets. So all the planets orbit in the same way.However they rotate in the opposite direction to the other planets.
Inner planets have a radius orbit shorter than the orbit of Jupiter. Outer planets are all the other planets of the solar system.
Because the Sun has a great gravitational pull on the planets. Without the Sun the planets would travel in straight lines (ignoring other gravitational forces in the Universe.)
the gravitational pull from the sun keeps the planets and other small things in the orbit of the sun.(;
Parts of other planets