The text discusses the formation of star-planet systems and how angular momentum plays a crucial role in shaping the system’s configuration. Here’s a simplified summary:
1. A massive clump of matter collapses under its own gravity, becoming asymmetrical with one axis longer than others.
2. The collapse causes the shortest axis to become pancaked, forming a disk shape around the central mass.
3. Angular momentum from tidal forces and initial mass distribution makes the disk rotate, leading to the formation of:
* A central clump of mass (the star)
* An orbiting disk of protoplanetary material
4. As the star forms, it heats up its core, causing nuclear fusion reactions that push radiation outward.
5. The external matter is heated from within, eventually forming planets through the condensation and growth of solid particles in the disk.
6. Planets can take on various shapes, such as spiral patterns and gaps, due to instabilities in the protoplanetary disk.
7. The initial conditions set by angular momentum and tidal forces make it likely for a system to form with planets.
The text concludes that this process is sufficient to explain the origin of motion in planetary systems, answering Newton’s question about who (or what) sets the planets in motion.
Source: https://bigthink.com/starts-with-a-bang/isaac-newton-oldest-question/