Why Is Solar System Flat?

Eventually, a portion of this material collapses toward the center, forming a star, and the spinning cloud begins to flatten into a disk due to the rotation. It’s out of this rotating protoplanetary disk of gas and dust that planets are born, resulting in a relatively flat solar system.Mar 18, 2021

How flat is the solar system?

The solar system is indeed pretty much a flat sheet, with the major planets all orbiting in a very thin plane surrounding the Sun. Part of the reason we don’t tend to send spacecraft in the ‘up’ direction, out of this thin plane, is simply that there’s not very much there!