Questions About Orbit

We’ve all seen the posters in school telling us the order of the eight planets and they’re all neatly put in a straight line; that seriously cannot be how the planets orbit the sun in a straight line some must be off in a tilt. So I went and tried to do some research and most sources do put all the planets in a somewhat near line not really varying from a straight rotation around the sun… Is that image correct do all the planets tend to rotate around the sun on an even plane if so then our solar system must be extremely flat with huge vast spaces closely above and below planetary rotations that are never occupied.

Indeed, the planets in our solar system orbit the sun in a relatively flat plane.  The largest mutual inclination between the orbital planes of two planets in our solar system is 7 degrees (out of a 360 degree circle).  There is even a special name for the plane in which the solar system planets orbit: the ecliptic plane.

We think the reason that the planets are in such a flat plane is tied to how planets form.  We think that our sun and its planets formed from a cloud of gas that collapsed.  The center of the cloud got hot enough to fuse hydrogen to helium; this part became our sun.  But what about the cooler outer layers of the cloud?  If the cloud had even a tiny bit of spin as it was forming, that spin would have been accelerated during the cloud’s collapse, like an ice skater who starts a slow spin, then brings her arms in to spin faster.  As the gas cloud collapsed and started spinning faster, much of the outer layers flattened into a disk in the same way that someone making a pizza crust spins the dough to flatten it into a pie.  After the gas cloud around the sun flattened into a disk, planets formed from that disk.  This is why the planets in our solar system have such flat orbits!  Here is a cartoon of the effect, and here is a short simulation video.

Best wishes!