1. Chapter 11: Pluto and Dwarf Planets

2. Pluto: Ruler of the Underworld Pluto was discovered by Clyde Tombaugh in 1930 by comparing one image of the sky taken one night with an image taken 6 nights later.

3. The discovery of Charon

4. HST discovers new moons! 2005 2011 2012

5. What is Pluto?

6. Strange planet; located far out from the Sun with gas giants but small size and very elliptical and highly inclined orbit Pluto is a mixture of ices and rocks composition similar to satellites of giant planets than terrestrial planets Could be captured Kuiper Belt Object (e.g. comet)?

9. A "planet" is a celestial body that: (a) is in orbit around the Sun, (b) has a nearly round shape (c) and has cleared the neighborhood around its orbit. 8 Planets ! IAU Definition

11. A “dwarf planet is” a celestial body that: (a) is in orbit around the Sun, (b) has a nearly round shape (c) and is neither a star, a planet, or a moon 40 + Dwarf Planets !

12. Should Pluto be a Planet? Write down the three characteristics of a planet. Why is Pluto not a planet anymore? What type of object is it? In your opinion, should we keep Pluto as a planet? Why or why not?