PX158 - H3 - planets

inner planets

• metallic core (chiefly iron and nickel)
• mantle composed of silicates
• secondary atmospheres due to outgassing (volcanism) and comet impacts

outer planets

• lower density, composed of hydrogen and helium
• metallic ($Fe,Ni$) and silicate core
• jupiter has a liquid hydrogen shell around its core
• primary atmosphere (gases accumulated during formation) of ammonia, carbon dioxide, and methane
• many moons

comets

• icy
• delivered molecules to planets via collisions