ASTR 101 Lecture Notes - Lecture 8: Nebular Hypothesis, Close Encounter, Radiometric Dating
29 Nov 2017
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Four major features needed to be explained. What properties of our solar system must a formation theory explain: patterns of motion of the large bodies, orbit in the same direction and plane. The nebular theory states that our solar system formed from the gravitational collapse of a giant interstellar gas cloud - the solar nebula. Nebula is the latin word for cloud. Kant and laplace proposed the nebular hypothesis over two centuries ago. A large amount of evidence now supports this idea. A rival idea proposed that the planets formed from debris torn off the sun by a close encounter with another star. That hypothesis could not explain observed motions and types of planets. Elements that formed planets were made in stars and then recycled through interstellar space. We can see stars forming in other interstellar gas clouds, lending support to the nebular theory. 8. 2 explaining the major features of the solar system.
