1. How are narrow rings thought to be kept from spreading out? 2. Compare the rings of Jupiter, Saturn, Uranus, and Neptune. 3. (a) What evidence suggests that Pluto is not a “normal” planet? (b) What evidence suggests that Eris is not a “normal” planet? 4. If Pluto’s surface temperature is 60 K, use Wien’s law to calculate the wavelength at which it gives off most of its thermal (black-body) radiation. In what part of the electromagnetic spectrum is this? 5. Eris Problem: Describe how/when Eris and Dysnomia were discovered 6. What creates the tail of a comet? Is something chemically burning? 7. How far is the Oort comet cloud from the Sun, relative to the distance from the Sun to Pluto? 8. Saturn Cassini Problem: Explore the Saturn Cassini homepage (http://saturn.jpl.nasa.gov/index.cfm) and describe, in 2 sentences each, any 2 discoveries by this probe. Also give the launch date, one sentence about the mission objective and one sentence about the spacecraft instruments.