2. Jupiter (Galileo)
Saturn (Cassini)
Uranus (Hubble)
Neptune (Voyager)

3. Everything You Need to Know about Ring Dynamics
Newton: Force = Mass x Acceleration
Law of Gravity
Collisions
Light-scattering Physics

5. Main ring
Dark side = High “phase angle”: emphasizes tiny dust grains

6. “Halo”
“Gossamer ring” discovery

7. Dusty rings must be sustained by source bodies
Two “Gossamer” rings
Dusty rings must be sustained by source bodies
(seen or unseen)

9. A B C D F
Encke Gap
Cassini Division
Lit side = Low “phase angle”: emphasizes large bodies

10. Earth!
Enceladus F
Unique high-phase view! G E

11. “Geysers” on Enceladus
= the source of the E ring

12. Cassini On-line Resources
Cassini Main Site
The latest raw images (cool!)
Imaging Team Web Site

13. The “Opposition Surge” on Saturn’s rings.
This appears exactly opposite to the direction to the Sun, at phase angle 0°.
The size of the surge is a measure of how rough the particles are.

15. The main rings of Uranus
Imaged by Voyager 2
Low phase = big particles
epsilon
lambda
delta
gamma
eta
beta
alpha
6, 5, 4

16. The rings of Uranus at high phase
> dust belts!

18. Uranus in HST

19. Long exposures reveal rings

20. Overlaying frames shows moons

21. Processing shows new rings!
nu ring
Mab & the mu ring

23. Adams
ring
Leverrier
ring
Fraternité
Egalité
Liberté
Courage

25. Neptune’s Changing Arcs
The arcs can now be detected by Hubble and ground-based telescopes.
Since 1989, the leading arcs have advanced forward and faded.
Gravity effects of the nearby moon Galatea help to confine the arcs
…but the model is in trouble!

26. Fun with Rings (1)
Vertical Ripples

28. D ring ripples that have been winding up since 1984!

29. Fun with Rings (2)
Satellite “Wakes”

30. Wavy edge of Encke
Gap suggests an
embedded moon.
Perturbed
central
ringlet
Color
enhancement
reveals “spiral”
structure.

31. The discovery
of Pan
in a sequence
of five
Voyager images

32. direction to Pan
A spectacular
view of
the Pan wake
from Cassini

33. Pan Imaged at Fine Resolution by Cassini

34. The Discovery of Daphnis in the Keeler Gap:
The wake is highly distorted

35. Saturn’s Pathological F Ring
Fun with Rings (3)
Saturn’s Pathological F Ring

36. Ophelia
Cordelia
Two moons “shepherd” the
epsilon ring of Uranus

37. Distant Voyager approach image:
Is the F ring shepherded too?
Pandora
Prometheus

39. A Selection of Cassini Images

40. Prometheus produces a “wake” pattern just like Pan

41. The aftermath of a ring impact?

42. A recent, new feature 200 km inward from the central ring

43. 2007: A Good Year ahead for Ring Science…

44. Cassini Extended Mission July 2008–June 2010
Sample Tour
Science planning is proceeding.
Note that this period includes the equinox on August 11, 2009!

45. New Horizons at Jupiter February 28, 2007

46. The first images of
Jupiter from New Horizons
Range is 1 AU

47. Sample planned images
during the
New Horizons flyby