Formation of Giant Planets If a young planetary body grows beyond a critical mass of about 10 Earth masses while still embedded in a gaseous disk, it will be able to "sweep up" a considerable amount of surrounding gas and will eventually become a giant gaseous planet like Jupiter or Saturn. Compared to terrestrial planets, the formation of giant planets must proceed very rapidly. This is because observations of many young stars (as well as some theoretical considerations) imply that disks around young stars have lifetimes of "only" one to ten million years. The time available for a giant planet to acquire enough mass is therefore relatively short, especially since the accretion process starts up rather slowly. It is therefore important that the "seed"-body rapidly reaches a "critical mass". A protoplanet moving in a large and therefore long orbit can collect more material than one moving closer to the central star. Giant planets are believed to form far away from the star at a distance where ices are present. Close to the star only silicates are present.

Life in the Universe
  Formation of Planetary Systems
    Planetary Formation
      Protoplanetary Disks (To be added soon!)
      The First Million Years
      The Next 100 Million Years
      Formation of Giant Planets
      Planet Migration