why do the planets all lie in a flat plane?

Answer 1

While the path of their rotations are almost planar, they are not in a perfect plane. Additionally, moons around the planets do not lie in that plane, nor do multiple moons fall into a unified plane around that planet.

Conventional wisdom holds that the majority of planets were created as ejected matter from the sun during it's creation. That ejected matter was thrown off from the rotation of the sun, and the matter which became the planets. The theory holds that the matter moving the fastest would have been thrown free at the "equator" of the sun, and that slower moving matter would not have been thrown free at high enough velocity to not be drawn back from the gravity of the sun.

Other objects, such as the planetoid Pluto, the planetoid which created our Moon, were likely just debris which was caught in a gravitational orbit after the formation of the solar system.

Answer 2

They do, because it makes the map of the solar system look good when viewed by children. Can you imagine looking at a map of the solar system when the planets are all over the place? It's there for simplicity but not necessarily a definition on what it would look like in real life. I guess it's possible for all planets to be aligned in one plane but highly unlikely.

Answer 3

It's easier to draw them that way. God was a smart dude.
(they really don't lie on a flat plane)

Answer 4

nope they dont.. If they did wheres the eclipse of planet mercury? And Earth would be blocking the light to Mars.

Answer 5

They all don't

Answer 6

no