 Over time, these larger objects continue to grow by accumulating matter from the disk. We find that in each region, each orbit, each distance from the Sun, everything coalesces into one massive object. These larger objects sweep out the remaining debris in their orbits. This is a defining characteristic for planets. All the little deviations averaged out as the smaller particles with varying elliptical orbits combined. This explains orbits being nearly circular and all in the same plane. But the actual process is very chaotic. Not as simple and straightforward as this illustration. The process of accumulating matter in the disk into larger objects came to an end when the Sun ignited as a main sequence star and its strong solar winds blew away any remaining loose material. Computer model estimates for how long this process takes range from 100 million to 200 million years. Here's a computer simulation created by Caltech that illustrates this chaos. Planets interact with the rotating disk and lose momentum moving their orbits closer to the Sun, or gain momentum increasing their orbital distance from the Sun. Changing orbits create collisions between planets, moons form and collide with each other and with planets, comets and asteroids form and smash into everything, but out of this chaos we get our current order.