Why do the planets all circle the sun on roughly the same plain? ?

Question

Why do the planets all circle the sun on roughly the same plain? ?

Answer 1

All planets circle the sun because of the laws of gravity. The planets were not formed from "another star" as the first poster so elegantly put it. They are all (with the exception of Pluto) formed out of the same star, our Sun. The Sun was once just a nebula cloud, eventual the center mass grew and formed our Sun. As time went on, the Sun created its own gravitational field, with varying degrees of strength. This pulled pieces of matter into the different strength zones, or rings. Again, as time went on, these small spheres of matter gathered more mass, until they became the planets we know today. They all basically orbit the same, with the exception of Pluto, which has a tilt to its orbit. Scientist have several theories why, but that is for another time.

Answer 2

The planets were formed from a dust cloud that was orbiting around the sun. This rotation spun out into a disc called the accretion disc. Therefore all of the planets made from this disc are in the same plain.

Some planets were not made in this manner. Some were "captured" by the Suns gravity and have eccentric orbits,  such as the case of Pluto which is not considered a planet now.

Answer 3

All the planets in our system cam from another star. After it expoded the dust became a disc.

Answer 4

All came from a disk of gas and dust cloud.So all go in the same direction and in the same plane.