Why is it that all the planets have orbits that are in the same 2d plane?

Question

AFAIK, all the planets orbit around the sun in the same 2d plane, perhaps with minor fluctuations.

I wanted to know why this was so. It sure seems coincidental and quite fantastic.

Answer 1

The solar system collapsed from a clump of dust and gas, and this clump must have had angular momentum -- that is, it was spinning to some extent. One of the laws of physics is that angular momentum is conserved, so the direction of spin of the original clump is still the direction of spin of the planetary orbits. (Also, the equator of the sun's rotation is in a similar plane.)

In reality, of course, you have all sorts of collisions and near-collisions happening -- particularly in the early solar system. For example, a small object might pass near Jupiter and be kicked into a very different orbit far out of the plane of the ecliptic.

So the current orbits (and also rotations) of the planets are the result of the original angular momentum of the proto-solar-system, as well as the gravitational encounters over the years.

One more thing: The same process must have applied to the galaxy as it formed from an enormous clump of gas. You might think that the solar system's plane should be similar to that of the galaxy, but it is not. I think the key difference is this: The entire solar system formed at one time, so there is a predominant ecliptic plane and axis of rotation. On the other hand, the formation of the sun occurred billions of years after the formation of the Milky Way, so its rotation was determined by local factors that were uncorrelated with the rotation of the galaxy.

Answer 2

No, it is actually easy to explain.

The planets wander in the same 2d plane because of the way they were formed. This solar system was once a big cloud of gas with a 'swirl' to it. The vortex came from the gas cloud's interaction with something else that imparted spin.

The spin stirred up the cloud to cause lots of collisions with the tiny particles of that cloud. But there is a law of physics called 'conservation of energy' - in this case, the energy of motion. So as the particles collided, if they stuck together they retained the motion brought on by the spin.

Well, if you have spin, that spin has an axis that is "normal" to the plane of the spin and everything SEEMS to spin around that axis. For the solar system, the 2d plane you mentioned is just the original spin plane.

OK, so leap ahead a few hundred million years as the cloud elements became larger and began attracting particles to themselves through gravity - because the number of particles in one small segment of space caused their gravitational fields (i.e. the gravity associated with each individual particle) to start adding in intensity. The more particles, the bigger the lump. Until it became a planet-sized lump. (Or eight full planets and some lesser lumps that didn't form so well.)

But because of the conservation of their energy of motion, they stayed in the same 2d plane that originated from the spinning gas cloud.

Nothing fantastic or mysterious about it at all.

Answer 3

Well, there are variations, including Pluto, which orbits at I believe about 17 degrees from the plane of the ecliptic. That is one of the reasons it was demoted to minor planet status.

But to answer your primary question, the reason the planets largely lie in the same plane (called the ecliptic) is that the matter from which they condensed formed in a ring around the early sun (due to gravitational forces). The impacts of planetesimals did knock many of the planets out of perfect orbits, but, owing to the relative size of the growing planets, were not significantly able to jar them from their orbits. Not to mention the fact that since most of the matter was moving in the same plane to begin with, there were not a large number of large objects moving at significantly different vectors to knock them out of position.

Answer 4

You're right, it isn't universal, at least in the Galaxy. But if you stop to think about it, it does make sense. After all, when the planets are forming in a solar system, they are a lot more likely to collide if they are flying around at right angles to each other. At some point, all the clumps of matter that become planets and moons will coalesce in orbits that don't cross each other. Hope this helps a little!

Answer 5

The question of why yields the biggest clue to how they have been shaped. fairly much all cutting-edge astronomers who study action picture star formation agree that, as element of action picture star forming technique, there ought to be a disk like circumstellar textile of dirt and gasoline. This disk is the construction block of the planet structures. The planets at the instant are not something extra advantageous than the trunks of the disk while it broke up as a results of gravitational instability

Answer 6

It's not really coincidental. It's what happens when you swirl a sphere of dust and gas around. The material tries to flatten out, and can clump into planets.

Answer 7

They all accreted from the same disc of gas and debris.

Answer 8

obital pattern all vary.. idon,t get you Lol..
and thier size and distance+suns grav effect whats your point?