Jupiter and Saturn
- Giant gas ball
- density ~ 1 gm/cm3
- c.f. terrestrial planets 3-5 gm/cm3
- Jupiter mass ~ 300 times Earth’s
- Jupiter 0.001 times the sun’s mass
Visible Atmosphere
- Primarily gaseous H2 and He
- traces of methane (CH4), ammonia (NH3), and clouds
- How do we know the composition?
- determined by spectroscopy from Earth
- confirmed by Galileo entry probe to Jupiter
- T ~ 100 K (cf. Earth ~ 300 K)
- radiates primarily in the Infrared region of the spectrum
- infrared features from methane, ammonia, ethane, etc. vg sp.