Why do the orbits of the planets all lie near the same plane?

Answer 1

poorcocoboiboi is correct.

I will only add that Pluto, which is now not a major planet, is an icy rock not in the plane with the other planets. This is one of the reason it was demoted.

Answer 2

Our solar system formed from a nebula of gas and dust that started to collapse due to any number of reasons (compression waves from interacting with other gas clouds or maybe gravitational waves from a nearby supernova). As it condensed it started rotating (conservation of momentum) and the energy of rotation forced the material into a disk. The sun formed in the central part of the disk where the material was densest, the planets formed from the leftover disk.
The planets and main asteroid belt therefore orbit within a narrow plane where the disk used to be (it's called the ecliptic).
Some planets orbits aren't completely in the ecliptic due to perturbations of the planets while or after they formed (due to interactions with other objects or from Jupiter's gravitational influence).

Answer 3

The dust cloud from which the Solar System formed was initially spherical. That cloud collapsed on itself as a result of gravitation. As it condensed, conservation of angular momentum caused it to rotate more quickly. Rotating bodies experience an apparent centrifugal force, which reduced the effect of gravitation perpendicular to the axis of rotation. Since the component of the gravitational field parallel to the axis of rotation was not diminished, the cloud condensed into a disc. This coalesced into the planets, so of course they all wound up along the plane of the ecliptic.

Answer 4

When the rocky debris that initiated the solar system crashed into the hydrogen field that became our sun,a giant smoke ring type structure was formed.
This whirling mass caused the hydrogen field to collapse starting the formation of the sun.
The rocky material was flung outward flattening into a disc preventing a chaotic distribution of the planets.

Answer 5

As the cloud of dust and gas that formed the solar system started to rotate, it kept colliding until it all ended up going the same direction, and thus in the same plane.

Answer 6

Well, since the sun rotates it generates more of its mass and gravity well at the equatorial region than at the poles.

Larger bodies tend to fall in line with the strong point of a gravity well.

Answer 7

Due to mutual attraction.

Answer 8

maybe they are not and its more of an artist conception thing