Why Hasn't the Kuiper Belt and Scattered Disc Coalesced into a Planet?

[FeynmanMH42]

Why has this not coalesced yet to form a planet?

 

[tony873004]

It never will. Eccentricities are too high, so any collisions would not be low-velocity. Collisions will grind things down instead of build them up. They also move very slowly, and the volume of space out there is huge, so collisions are not even that likely.

 

[sir-pinski]

The Kuiper belt and scattered disc are two distinct regions in the outer solar system that are home to numerous small icy bodies, including dwarf planets, comets, and asteroids. These regions are located beyond the orbit of Neptune and are believed to be remnants of the early solar system.

One of the main reasons why these regions have not coalesced to form a planet is due to the gravitational influence of the gas giants, particularly Neptune. The strong gravitational pull of Neptune causes the objects in the Kuiper belt and scattered disc to have highly elliptical orbits, making it difficult for them to come together and form a single, cohesive body.

Additionally, the objects in these regions are made up of mostly ice and other volatile substances, which are easily affected by the heat and radiation from the Sun. This makes it challenging for them to clump together and form a solid planet.

Another factor that prevents the formation of a planet in the Kuiper belt and scattered disc is the relative lack of collisions between objects. In the early solar system, collisions between objects were more frequent, leading to the formation of larger bodies. However, as the solar system has evolved, these collisions have become less common, hindering the growth of larger objects.

Overall, the combination of the gravitational influence of Neptune, the volatile nature of the objects, and the lack of collisions have prevented the Kuiper belt and scattered disc from coalescing into a planet. However, ongoing research and observations in these regions may shed more light on the formation and evolution of these distant regions of our solar system.