Chapter 8: Formation of the Solar SystemWhat properties must solar system formation theory explain:Monday, January 14, yChapter 8: Formation of the Solar SystemWhat properties must solar system formation theory explain:-Patterns of motion of the large bodies-existance of two types of planetsThe nebular theory best explains all of these features-The nebular theory states that our solar system formed from the gravitational collapseof a giant interstellar gas cloud- the solar nebula-nebula is the latin word for cloud-Part of a cloud gravitationally collapses;desnse concentration at the center becomes a star-elements heavier than H, He were created in stars: “gelactic recycling:-Solar systems form from interstellar gas clouds-Dust makes clouds look dark and is dreaded with 98% H and He• we can see stars forming in other interstellar gas clouds-initial clump within cloud will have small amount of rotation-rotation speed increases as the cloud contracts• conservation of angular momentum• Collapsing cloud flattens-colissions between gas particles reduce up and down motions1Monday, January 14, y-collisions also reduce random motions-results in a rotating disk of material-So now we have a star surrounded by a disk, then what?• this is how planets form. how>• dust and ices stick and grow into the seeds of planets- planetesimals-dust and ice are only a small amount of total mass, but are needed to seed planet growth• Once large enough planetesimal begin gravitationally attracting disk material and grow into planets-this process of assembly is called accretion-(we don’t know how they grow into larger sizes)-Its gravity develops helps to attract more things into orbit• Although 98% of mass, H and He do not instigate planet formation• Outside of the frostline rocks and metals condense but it’s too hot for hydrogen om-poounds to form ices. Outside the frost line hydrogen compounds, rocks and metalsall condense-frostline is at about 4 AU in our solar system between the orbits of mars and Jupiter-Terrestrial planet formation• planetesimals build up from available solids• gravity assembled these into planets2Monday, January 14, y• never became masses enough to attract H and He-Jovian planet formation• more solids • gravity of these larger planets attracted surrounding H and He gas, allowing them togrow very massive-Why did planet formation end-in the first 10 million years, disk material was accreted on the central star or went into making planets-The planets formed out of disk of material (mostly H and H gas) that surrounded the young sun. Terrestral planets formed inside the frost line and Jovian planets formed outside the frost line.Scenario explains the solar system’s propertiesI. Planets forming in a disk explains coplanar orbitsII. condensation temperatures explain terrestrial and Jovian planet differencesIII. Heavy bombardment phase explains these exceptionsScenario explains the solar systems propertiesI. Swarms of smallr bodies are likely planetesimals that never formed planetsA. It’s likely Earth’s water came from cometsTHe Age of the solar system•Is determined from the age of the oldest rocks in our solar system•the age of a rock is the time since it last solidified3Monday, January 14, y•Meteroites are solid pieces of rock that originates from space and survives it’s im-pact with the Earth’s surface•Radiometric dating- a method for estimating the age tom radioactive decay•The more argon in the rock, the older it must be•Oldest Moon rocks are 4.4 billion years•oldest meterorites are 4.5 billion years•Planets probably formed 4.5 billion years