• The basic reason for the heliocentric system or why the planets revolve around, or orbit the sun (rotate actually is used to describe their spin, for example, the Earth completes one rotation about its axis every 24 hours, but it completes one revolution around the Sun every 365 days), is that the gravity of the sun keeps them in their orbits. Just as the Moon orbits the Earth because of the pull of Earth's gravity, the Earth orbits the Sun because of the pull of the Sun's gravity. Many scientists believe that our solar system started out as a cloud of dust and gas called the solar nebula. It is thought that a stellar explosion called a supernova happened near the solar nebula causing it to collapse inward. As it collapsed, it flattened out into the shape of a disc and started spinning. The material in the center of the disc collapsed on itself. This created enough pressure to start a nuclear reaction that formed the Sun. The materials toward the outside of the disc collided with each other and stuck together forming our planet. The planets continued to travel in the same path that the disc had been spinning in before. Even though the planets grew in size and became able to spin off their own, the Sun at the center was larger and kept them right where they were with its very strong gravitational pull. Why, then, does the Earth travel in an elliptical orbit around the Sun, rather than just getting pulled in all the way? This happens because the Earth has a velocity in the direction perpendicular to the force of the Sun's pull. If the Sun weren't there, the Earth would travel in a straight line. But the gravity of the Sun alters its course, causing it to travel around the Sun, in a shape very near to a circle. This is a little hard to visualize, so let me give you an example of how to visualize an object in orbit around the Earth, and it's analogous to what happens with the Earth and the Sun. Imagine Superman is standing on Mt. Everest holding a football. He throws it as hard as he can, which is incredibly hard because he's Superman. Just like if you threw a football, eventually it will fall back down and hit the ground. But because he threw it so hard, it goes past the horizon before it can fall. And because the Earth is curved, it just keeps on going, constantly "falling," but not hitting the ground because the ground curves away before it can. Eventually the football will come around and smack Superman in the back of the head, which of course won't hurt him at all because he's Superman. That is how orbits work, but objects like spaceships and moons are much farther from the Earth than the football that Superman threw. This same situation can be applied to the Earth orbiting the Sun - except now Superman is standing on the Sun (which he can do because he's Superman) and he throws the Earth.
  • Thru gravitational attraction.....which till this day can still not be explained.....all the top scientist in the world have given this strange attraction of the planets and the sun , and whole galaxies.......a name ....but nobody can figure out how it actually works........if they knew......we would of developed antigravity by now.
  • There is a theory that the planets don't actually "revolve" around the sun. According to Einstein's theory, any mass warps space around it. (Imagine a heavy lead ball placed on a bed. The surface of the bed will bend/sag below the ball and the ball will sink into a depression. The ball represents the mass, and the bed represents space.) Therefore, the planets, relative to themselves, are actually following a straight line. But since the sun (a mass) warps space around it, the planets appear to follow a circular path around the sun. But to answer your question at our level, any two masses exert gravitation forces on each other (Newton's Law of Universal Gravitation). Therefore the force of attraction between the sun and the earth is large enough to make the earth veer off from the straight line path that it would have otherwise followed by Newton's First Law and to make it follow an ellipsis.
  • Because according to Newton's Uneversal Law of Gravitation all things are "attracted" to one another. However, because the sun has so much mass. Plus, it is not completely stationary it becomes the obect ,that is being revolved around. The Sun is attracted to the planets, and the planets are attracted to the Sun. The link at the bottom of my answer describes the mechanics involved. Here's a nice source to consult, if you are in need of furthur assitance.
  • A year has 31536000 seconds. ever guessed why does the figure resemble "pi"x10^7 seconds. the difference is only because the path is not perfectly circular. U can obtain it easily by equating mv^2/r and newton's gravitation equation f=GMMe/r^2
  • what would happen is the earth stoped revloving around the sun?
  • The sun and the planet attract each other because of their gravitational force.. but because of the planet's revolutionary movement, the planet is acted upon a centrifugal force, which then balances the gravitational force.. if there were no revolutionary movement of the planet, the sun and the planet would just collide, due to their gravitational pull... its the same case of the international space station, which has to continously revolve the earth, to prevent itself from falling towards earth... any other answers guys?... this is what i think....
  • 2-9-2017 When you observe something, that is science. When you ask why, that is religion.

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