What compositional pattern distinguishes the inner terrestrial planets from the outer giant planets?
Inner planets are rocky/dense, while outer planets are large and rich in gas/ice.
The temperature gradient established across the solar nebula disk directly dictated the chemical zoning observed in the Solar System today. Near the proto-Sun, high temperatures ensured that only materials with high melting points, specifically metals and silicates (rock), could condense into solid grains. This led to the formation of the small, dense, rocky inner worlds: Mercury, Venus, Earth, and Mars. Farther out, past the frost line, temperatures allowed ices to form alongside rock and metal. This abundance of solid material allowed Jupiter, Saturn, Uranus, and Neptune to grow massive enough to gravitationally dominate and sweep up the remaining light gases (hydrogen and helium), resulting in the large, gas-and-ice-rich outer giants.
