Jupiter and Saturn
Giant (Jovian, outer) planets
- ~ 10 times the diameter of the Earth
- ~ 1/10’th the diameter of the Sun vg 63
Formed further from the Sun
- Temperature lower
- “ice zone”, water ice solid Z 86
- 2-3 times as much material to form “planetesimals” Z 85
- km sized bodies of accreted rock and ice dust grains
- gravity-assisted accretion eventually grows a “protoplanet”
- Gravity (i.e. escape velocity) and low T’s promote attraction and retention of H and He gasses vg 68
- H + He represent ~ 98% of the mass of the solar nebula
- the sun is 98% H and He by mass
- Jupiter and Saturn composition very close to the Sun