1. Review: the giant planets and their moons

2. Comparing the planets
These can be divided into two groups: terrestrial and Jovian
The differences are obvious in Mass, Radius, and Average Density

3. Early Solar System Temperatures
Differentiation in the early solar system caused most of the
lighter material to condense out near Jupiter and Saturn

4. Jupiter Most of what we have learned about the Jovian planets has
come from spacecraft.
Voyager I and II
Galileo spacecraft and probe
Cassini spacecraft and
the Huygens probe

5. Gravitational “Slingshots” are used for missions to the outer planets, to save energy or to allow heavier payloads.

6. Gravitational “Slingshots” were very successful in the Voyager missions to all four Jovians.

7. Jupiter’s Interior

8. Jupiter’s Atmosphere
We know some things about the upper layers of Jupiter’s atmosphere from the probe that was carried by the Galileo spacecraft.
It survived until it was about 150 km below what we call the “surface” of Jupiter.

9. Jupiter’s atmosphere has very obvious bands

11. Jupiter’s Convection
Jupiter radiates about twice as much heat as it absorbs from
the Sun, so the extra heat is coming from the interior. This
creates Jupiter’s weather as the heat moves up from the interior.

12. Jupiter’s Red Spot is a very long-lived storm
We first observed Jupiter’s Great Red Spot over 300 years ago

13. Jupiter’s Brown Oval was a temporary feature
All jovian planets have
differential rotation of
their atmospheres. So
the rotation depends
on the latitude.

15. The Pioneer 10 spacecraft studied the magnetic fields
All the Jovian planets have
extensive magnetic fields
Jupiter’s extends well past
the orbit of Saturn!

16. Aurorae on Jupiter
Aurorae have been
seen on both
Jupiter and Saturn.
These are caused
by the solar wind
interacting with the
magnetic field of
the planet.

18. A Cometary Impact on Jupiter was seen in 1994.

19. Shoemaker-Levy 9 Comet Impact with Jupiter
Tidal forces from Jupiter caused
this comet to break up into a row
of smaller objects. Then on a
later orbit the fragments hit the
atmosphere of Jupiter in 1994.

20. Shoemaker-Levy 9 Comet - Fragment G hit Jupiter.
The impact left a huge dark mark in the atmosphere.

21. Moons of the solar system:
3 categories: 7 large (each is distinctive) medium-size
many small (most are captured)

22. Io Europa Ganymede Callisto
Galilean Moons of Jupiter, shown in relative size. Two are similar in size to our Moon; two are similar in size to Mercury.
Io Europa Ganymede Callisto

23. Galilean Moon Orbits

24. Galilean Moon interiors are quite distinct from each other

25. Io is the most volcanic object in the solar system, due to tidal forces between Io, Europa, and Jupiter

26. Io
Notice
the large
ring of
volcanic
ejecta
around
a volcano

27. Io A volcanic plume is seen on the left limb. The plume is
about 150 km high.

28. Io
A volcanic
eruption is
seen in a
caldera.

29. Europa, with an enhanced image on the right.
A thick layer of ice covers the entire surface.
An ocean under this layer might support life.

32. Ganymede is the largest moon in the solar system

33. Ganymede has an icy surface with cracks similar
to those seen on Europa and other moons.
The surface is older, darker, and has more craters.

34. Callisto has an even older and darker surface.

35. Jupiter’s
Red Spot
compared
to the sizes
of the four
Galilean moons
(in a photomontage)

36. Saturn Cassini is currently in orbit around Saturn and
is continually sending
back more data about
Saturn and its moons.

37. Comparison of Saturn with Earth and Earth-Moon distance

39. Saturn’s atmosphere is similar to Jupiter’s
Saturn’s atmosphere is similar to Jupiter’s. Although we sent a probe into Jupiter’s atmosphere, we are just guessing about Saturn. (Cassini data will be coming out soon.)

40. Uranus and Neptune
Just one spacecraft (Voyager II) visited Uranus and Neptune.
Both planets get their bluish color from methane in their
atmospheres.

41. Uranus’s seasons are extreme due to its tilt

42. Jovian interiors
Uranus and Neptune are sometimes called the “ice giants” because
they have larger amounts of water ice, ammonia, and methane.

43. Jovian magnetic fields
Uranus’ and Neptune’s magnetic fields have strange orientations,
and are not at all aligned with the rotation of the planet.
Saturn’s magnetic field is perfectly aligned.

45. Planetary Rings
Rings around planets are important to understand because they allow us to test theories about the formation of the solar system.
The early solar system was a disk-shaped nebula around a protostar, and it very likely had some of the features that we see today in the rings of the Jovian planets.
The capture of ring material by shepherd moons, or the clearing of gaps in the rings, are critically important to the accretion process that formed large objects in the solar system nebula.

46. Saturn over four years of observation.

47. The Roche Limit is the radius at which a moon will fragment into pieces due to the tidal force and form the fragments that make up a ring.

48. Jovian Ring Systems are inside the Roche limit

49. Saturn’s rings, first quarter of full image.

50. Saturn’s rings, second quarter of full image.

51. Saturn’s rings, third quarter of full image.

52. Saturn’s rings, fourth quarter of full image.

53. Shepherd moons control the dynamics of parts of the ring.

54. The Encke gap in the rings, showing a twisted thin ring in the gap.

55. The Encke gap in the rings of Saturn
The Encke gap in the rings of Saturn. Notice the spiral structure on the inner edge.

56. A shepherd moon causes waves in the
edges of the Keeler gap in the rings of Saturn.

57. Jupiter’s faint rings were seen again in 2007 by the New Horizons spacecraft on it way to Pluto.

58. Rings of Uranus top picture shows detail of the outermost ring

59. Two shepherd moons were seen in one photo taken by the Voyager II spacecraft as it went by Uranus.

60. Neptune’s faint rings were seen in one photo from Voyager II.

61. The significance of Rings
Rings around planets are important to understand because they allow us to test theories about the formation of the solar system.
The early solar system was a disk-shaped nebula around a protostar, and it very likely had some of the features that we see today in the rings of the Jovian planets. (It was probably much thinner than the artists drawings!)
The capture of ring material by shepherd moons, or the clearing of gaps in the rings, are critically important to the accretion process that formed large objects in the solar system nebula.

62. On Nov. 5, 2014, the ALMA observatory (in Chile) announced that they had obtained an image of a protoplanetary disk around a distant star.
See the
ALMA
website
for details
(link)