AS101 Lecture Notes - Lecture 10: Ecliptic, Planetary Migration, Gliese 581
Document Summary
The nebular theory states that our solar system formed from the gravitational collapse of a giant interstellar gas cloud the solar nebula. Kant and laplace proposed the nebular hypothesis over two centuries ago. A large amount of evidence now supports this idea. Predictions of this theory have been accurate. Solar nebula was initially a cold low density cloud of gas of diameter 100-200 au. Collapse of the gas may have been triggered by a cosmic event such as the shock wave of a nebula. Initial slow rotation speed of the cloud increased as the cloud contracted (ice skater) The cloud heated up as it contracted. The sun formed at the center where temperatures and densities were highest. Observation of disks around other stars support the nebular hypothesis. The spinning disk explains the uniform motion observed in the solar system today planets all orbit the same direction of the spin of the disk they were formed from.
