Why are all planets in the solar system aligned like a pancake, rather than in a sphere surrounding the sun?

Question

Why are all planets in the solar system aligned like a pancake, rather than in a sphere surrounding the sun?

In: 12

Answer 1

So the solar system started off as a big cloud of collapsing dust. By sheer statistical probability on average everything will average out to be slightly rotating around one axis.

During the collapse dust hits other dust, bigger blobs hit other blobs, and each time their angular momentum combines had brings it closer to the average.

Things orbiting at a tilt or orbit against the average in general have more chances to hit and cancel out as well.

So by the time we have the sun and planets mostly formed all the angular momentum left leaves everything in a plane orbiting around that original axis of average angular momentum.

Some smaller things, again just by chance ended up tilted a bit, not in circular orbits, etc and toward the end of the solar system formation there just wasn’t enough stuff spread out to hit anymore.

There are also some objects and anomalies like planet axis tilts that were a result of large collisions after things we’re mostly formed.