1. The Jovian Planet Systems
TOTALLY different planets than our familiar next door neighbors!
The formed beyond the frost line – so ices could form and seed the early stages of agglomeration. There’s a lot more ice-type raw material than rock-type raw material, so you get bigger planets!

2. Remember How a Planet Retains an Atmosphere
Surface gravity must be high enough and
surface temperature must be low enough, that the atmosphere molecules don’t leak away during the 4.6 billion years since formation.
Also,Jovian Planets are so distant and so cold, they formed from seeds of ice, MUCH more common than rocky seeds
Net Result: Jovians are mostly atmosphere or (in Jupiter’s case) liquid hydrogen

3. Two Ways a Planet Loses Atmosphere: First…Leakage!
Lighter molecules move faster, because on average Kinetic Energy = Thermal Energy
(½)m<v>2 = (3/2)kT
For a given temperature, higher mass molecule means lower velocity molecule, is what this equation is telling us
So the lighter gasses leak away more quickly over time
Molecules are continually bouncing off of each other and changing their speed, but if the average speed is higher, a few may be speedy enough to escape the planet’s gravity.
So…. Slow leak! Like air from a bicycle tire
Hydrogen and Helium = 97% of the mass of the solar nebula, and these are the lightest and easiest molecules to lose.
But they are NOT lost by Jupiter, Saturn, Uranus and Neptune. Mass is high, gravity is high, escape velocity is high, and temperature is low so molecular velocities, even H2 and He, is also low.

4. The Second way to Lose Atmosphere…
Impact Cratering! Big comets and asteroids hitting the planet will deposit a lot of kinetic energy which becomes heat, blowing off a significant amount of atmosphere all at once.
This is a big issue especially in dense areas (inner solar system), and dense times (soon after formation).

5. The Outer Plants: Hydrogen/Helium Giants
97% of early solar nebula was hydrogen and helium, roughly the composition of the outer planets
Cold temperatures, high mass allow these light atoms to be held by gravity for these 4.6 billion years
Rocky cores surrounded by deep layers of H, He.

6. Jupiter,Saturn,Uranus,Neptune lineup

7. Jupiter layers

8. magnetosphere

9. Jupiter redspots

10. Jupiter storms

12. GRS storms

13. Jupiter gives off more heat than it receives from the sun
Jupiter gives off more heat than it receives from the sun. It’s HOT under that cold atmosphere
Why? Heat of formation takes a LONG time to dissipate, but mainly its because it is still slowly collapsing, converting gravitational potential energy into heat
You can see the hotter layers in infrared pictures…

14. Jupiter IR, excess heat

15. Jupiter ring

16. Jupiter + Io

17. Jupiter’s Moons – Dozens of them
The big ones are roughly the size of our own moon – 1500 – 3000 miles across
Io, Europa, Ganymede and Callisto
Io’s orbit is a bit elliptical, and only a couple Jupiter diameters away from Jupiter – this has a huge effect on the properties of this little moon

18. Io globe

19. Jupiter’s gravity and the closeness of its moons makes for a strong tidal force
This tidal force varies from weaker to stronger as Io goes from closer to farther from Jupiter. This rhythmic squeezing of the moon heats the interior – tidal friction
It’s surprisingly effective. The volcanoes have vent temperatures of 2000F, melting sulfur, a relatively light element that is rich in the upper layers, and vaporizing any water or other icey type materials.

20. Io cutaway

21. Io globe closer in

22. Io volcano

23. Io pele

24. Io volcano on limb

25. Io volcano closeup

26. Io surface hi res

27. Summary on Io
Io is stretched more, then less, then more, then less…etc for each and every orbit.
This converts orbital energy into thermal energy, heating the interior above the melting point of sulfur (239F or 115C), and it burbles up through cracks to make volcanoes.
Constant volcanic eruptions quickly fill in all craters that may have existed

28. Europa – Also tidally heated, but less so
It was able to hold on to water, which was not so hot as to evaporate away. Water is a very common molecule…
Cracks show characteristics of salt-water pressure ridges

29. Europa interior cutaway

30. Europa cracks

31. Europa cracks

33. Lake Vida Antarctic

34. ganymede

36. Ganymede globe gray

37. Callisto ice spires

38. Callisto globe

39. Callisto cratering

40. Jupiter small rocky moons

41. saturnHST

42. Saturn hst2

43. Saturn rings

44. Mimas and rings

45. Cassini division close up

46. Saturn dragon storm

47. Saturn aurorae

48. Saturn aurorae sequence

49. Titan haze from side

50. Titan color

51. Titan b&w oceans

52. Titan shorelines

53. titan

54. Titan ocean+canyon

55. Titan impact crater

56. Titan bouldersColor

57. phoebe

58. Enceladus-all

59. Enceladus surface wedge

60. Enceladus surface

61. Enceladus surface2

62. Enceladus cracks

63. Mimas

64. Rhea cassini

65. iapetusWalnut

66. iapetus

67. Hyperion spongeBob

68. saturnMoonEpithemus

69. Uranus, rings in ir

70. Uranus,ringsHST

71. oberon

72. Miranda lowres

73. Miranda hi res

74. Miranda bullseye

75. Miranda cliff

76. Neptune HST

77. Neptune great dark spot

79. triton