ASTR 101 Lecture Notes - Lecture 6: Tidal Heating, Galilean Moons, Protoplanetary Disk
Document Summary
All planets appear to orbit in the same general plane (the ecliptic plane) and in the same direction. The non-random arrangement makes it clear that the planets must have formed at the same time. There was some preferred plane and axis of rotation. Solar nebula model: the planets must have been formed in a flattened, rotating disk of material in which protoplanets accreted mass till they reached their current sizes. The disks are seen to exist elsewhere, mostly made of hydrogen and helium, along with carbon and silicate dust, in regions where stars are known to be forming such as the great nebula in orion. As giant gas clouds that form clouds begin to collapse under their own gravity, they spin faster which shapes the cloud into a disk (known as a protoplanetary disk) In our solar nebula, the material accreted, preserving orbital and angular momentum of the particles that formed them.
