1. Chapter 7 The Jovian Planets

2. 7.1 Observations of Jupiter and Saturn
Jupiter can be imaged well from Earth, even with a small telescope
Here: Jupiter with its Galilean moons

3. 7.1 Observations of Jupiter and Saturn
True color image of Jupiter

4. 7.1 Observations of Jupiter and Saturn
Natural-color image of Saturn

5. 7.1 Observations of Jupiter and Saturn
Cassini image of Jupiter, true color

6. 7.2 The Discoveries of Uranus and Neptune
Uranus, in natural color. Note the absence of features.

7. 7.2 The Discoveries of Uranus and Neptune
Neptune in natural color

8. 7.3 Bulk Properties of the Jovian Planets
The Jovian planets are large and much less dense than the terrestrial planets

9. 7.3 Bulk Properties of the Jovian Planets
The Jovian planets are large and much less dense than the terrestrial planets
Saturn is less dense than water!

10. 7.3 Bulk Properties of the Jovian Planets
The Jovian planets are large and much less dense than the terrestrial planets
Saturn is less dense than water!
And they spin faster

11. 7.3 Bulk Properties of the Jovian Planets
Jovian planets, compared to Earth

12. 7.3 Bulk Properties of the Jovian Planets
Peculiarity of Uranus: axis of rotation lies almost in the plane of its orbit. Seasonal variations are extreme.

13. 7.4 Jupiter’s Atmosphere
Atmosphere has bright zones and dark belts

14. 7.4 Jupiter’s Atmosphere Atmosphere has bright zones and dark belts
Zones are cooler, and are higher than belts

15. 7.4 Jupiter’s Atmosphere Atmosphere has bright zones and dark belts
Zones are cooler, and are higher than belts
The result of convection

16. 7.4 Jupiter’s Atmosphere Atmosphere has bright zones and dark belts
Zones are cooler, and are higher than belts
The result of convection
Stable flow underlies zones and bands, called zonal flow

17. 7.4 Jupiter’s Atmosphere
We know a good deal about the nature of the upper Jupiter atmosphere from a probe dropped from the Galileo orbiter

18. 7.4 Jupiter’s Atmosphere
We know a good deal about the nature of the upper Jupiter atmosphere from a probe dropped from the Galileo orbiter
The arrow indicates the probe’s entry point.

19. 7.4 Jupiter’s Atmosphere
No solid surface; take top of troposphere to be 0 km

20. 7.4 Jupiter’s Atmosphere
No solid surface; take top of troposphere to be 0 km
Lowest cloud layer cannot be seen by optical telescopes

21. 7.4 Jupiter’s Atmosphere
No solid surface; take top of troposphere to be 0 km
Lowest cloud layer cannot be seen by optical telescopes
Measurements by the Galileo probe show high wind speeds – up to 500 km/h – even at great depth – probably due to heating from planet, not from Sun

22. 7.4 Jupiter’s Atmosphere Major visible features:
Bands of clouds; Great Red Spot:

23. 7.4 Jupiter’s Atmosphere
Great Red Spot: First observed by Giovanni Cassini or Robert Hooke ~1665

24. 7.4 Jupiter’s Atmosphere
Great Red Spot: It is a very long-lived storm, with winds spinning CCW, like a hurricane, sort of…

25. 7.4 Jupiter’s Atmosphere
Great Red Spot: It is a very long-lived storm, with winds spinning CCW, like a hurricane, sort of…but what exactly is a hurricane???

27. The Coriolis Effect

28. The Coriolis Effect and Storms

29. The Coriolis Effect and Storms
Low pressure storms circulate CCW in northern hemisphere, CW in southern hemisphere

30. The Coriolis Effect and Storms
The Great Red Spot is in the southern hemisphere
And the winds go CCW
Therefore it is a high-pressure storm

31. 7.4 Jupiter’s Atmosphere
Lightning-like flashes have been seen; also shorter-lived rotating storms
One example: Brown Oval, really a large gap in clouds
Jupiter’s atmosphere is very dynamic

32. 7.5 The Atmospheres of the Outer Jovian Worlds
The atmosphere of Saturn is similar to that of Jupiter, except that Saturn is somewhat colder.

33. 7.5 The Atmospheres of the Outer Jovian Worlds
Saturn’s atmospheric pressure is also lower
Three cloud layers
Cloud layers are thicker than Jupiter’s; see only top layer

34. 7.5 The Atmospheres of the Outer Jovian Worlds
Jupiter
Saturn

35. 7.5 The Atmospheres of the Outer Jovian Worlds
Jupiter-style “spots” rare on Saturn; don’t form often and quickly dissipate if they do

36. 7.5 The Atmospheres of the Outer Jovian Worlds
Jupiter-style “spots” rare on Saturn; don’t form often and quickly dissipate if they do
Winds are even higher than on Jupiter – up to 1500 km/h

37. 7.5 The Atmospheres of the Outer Jovian Worlds
Storms near Saturn’s equator:

38. 7.5 The Atmospheres of the Outer Jovian Worlds
“Dragon” storm on Saturn – apparently a vast thunderstorm

39. 7.5 The Atmospheres of the Outer Jovian Worlds
Rotation of Uranus can be measured by watching storms

40. 7.5 The Atmospheres of the Outer Jovian Worlds
Neptune has storm systems similar to those on Jupiter, but fewer. The large storm system at top has disappeared in recent years:

41. 7.6 Jovian Interiors
No direct information is available about Jupiter’s interior, but its main components, hydrogen and helium, are quite well understood. The central portion is thought to be a rocky core.

42. 7.6 Jovian Interiors
Jupiter compared to the other jovian planets

43. 7.6 Jovian Interiors Jupiter compared to the other jovian planets
Saturn has a similar structure, but less metallic hydrogen

44. 7.6 Jovian Interiors Jupiter compared to the other jovian planets
Saturn has a similar structure, but less metallic hydrogen
Uranus and Neptune have no metallic hydrogen

45. 7.6 Jovian Interiors
Since Uranus and Neptune have no metallic hydrogen, their magnetic fields are hard to understand

46. 7.6 Jovian Interiors
Since Uranus and Neptune have no metallic hydrogen, their magnetic fields are hard to understand
They might be due to slushy water solutions of ammonia, which would be electrically conducting

47. 7.6 Jovian Interiors Jupiter’s magnetosphere:
Intrinsic field strength is 20,000 times that of Earth
Magnetosphere can extend beyond the orbit of Saturn:

48. 7.6 Jovian Interiors
Aurorae are seen on Jupiter, and have the same cause as those on Earth – the interaction of solar wind particles with the magnetosphere

49. 7.6 Jovian Interiors
Uranus and Neptune both have substantial magnetic fields, but at a large angle to their rotation axes.
The rectangle within each planet shows a bar magnet that would produce a similar field. Note that both Uranus’s and Neptune’s are significantly off center.

50. Summary of Chapter 7
Jupiter and Saturn were known to the ancients; Uranus was discovered by chance, and Neptune was predicted from anomalies in the orbit of Uranus
Jovian planets are large but not dense; they are fluid and display differential rotation
Cloud layers have light zones and dark bands; wind pattern, called zonal flow, is stable

51. Summary of Chapter 7
Storms appear with regularity; the Great Red Spot of Jupiter has lasted for hundreds of years (that we know of)
Due to conductive interiors and rapid rotation, Jovian planets have large magnetic fields
Jupiter, Saturn, and Neptune radiate more energy than they receive from the Sun