Solar System All masses that orbit the sun plus the sun!

Solar System Contents Sun (most of the mass!) Planets and their satellites Asteroids (asteroid belt) Comets (Oort cloud) Gas and dust (all over!)

Terrestrial Planets Earthlike: rocks, metals Solids and fluidlike materials Surfaces that record change Small sizes, but high densities Inside asteroid belt

Jovian Planets Jupiter-like: Liquids & gases No solid surfaces to preserve changes Large sizes, low densities, made mostly of hydrogen and helium Outside asteroid belt

Planet Models Mass & spherical shape (Newton’s law of gravitation) Radius (from angular size and distance) Bulk density (mass/volume) => infer general composition Contain density layers (lowest, surface; highest, core)

Evolution of Planets Heat (energy flow)! Heat goes from hotter to cooler regions Drives internal & surface change Eventually radiates into space

Energy Transfer Conduction (solids; adjacent particles collide) Convection (fluids; lower density blobs rise) Radiation (radiate energy, emitted and absorbed)

Internal Evolution Energy flow from core to surface to space Source: Stored energy of formation, radioactive decay Results in volcanism, tectonics on solid surfaces (terrestrial); convection in liquids & gases (Jovian)

External Evolution Impact cratering: Solid objects from space, hit at tens km/s Bomb-like explosion; many megatons (H-bomb!) Creates circular impact craters on solid surfaces; turbulent regions in liquids