ASTRON 1F03 Lecture Notes - Lecture 6: Solar Wind, Planetesimal, Oort Cloud
18 Dec 2015
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Document Summary
Can gas disks break-up into clumps that collapse to planets: not if the gas is too hot to compress. What about all that gas near the rocky planets: rocky planets form from only the dust. Within the disk, small particles collide and stick. Small particles are blown into larger ones by gas motions. This leads to larger particles, about 1km, called planetesimals. Dust particles in the solar nebula disks can stick together. 1km sized in 100,000 years: origin of asteroids and comets! At 1km and up gravity is important. Larger objects quickly gobble up most material until there are many moon sized planet embryos . It takes a long time but eventually most of the embryos collide to form well separated planets. Most planets revolve and rotate in the same way around the sun. The inner planets had very large collisions during their creation, enough to change their rotation a great deal.
