Planets, Dwarf Planets and the Exploration of Pluto

1. Planets, Dwarf Planets and the Exploration of Pluto

2. Planet definition: A celestial body that:

3. Planet definition: • A celestial body that: • is in orbit around the Sun

4. Planet definition: • A celestial body that: • is in orbit around the Sun • (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly spherical shape; and

5. Planet definition: • A celestial body that: • is in orbit around the Sun • (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly spherical shape; and • (c) has cleared the neighborhood around its orbit;

6. Planet definition: • A celestial body that: • is in orbit around the Sun • (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a nearly spherical shape; and • (c) has cleared the neighborhood around its orbit; • If only (a) and (b) are met, it is a “dwarf planet”

7. Dwarf Planets

9. Pluto – 39.5 AU - Discovered in 1930 - Composition and size similar to Triton (2/3 size of our Moon) - 50 K surface temperature - highly elliptical orbit - axis of rotation tilted 118o - One large moon: Charon, 2 newly discovered small ones (Nix & Hydra)

10. Pluto has a highly inclined orbit (17o to ecliptic) Pluto 17o Earth

11. Pluto has a highly elliptical orbit 1979 Neptune 1999 Pluto

13. Charon Pluto

14. Nix Hydra

15. “New Horizons” Launched: January 19, 2006 Arrival at Pluto: July 2015

16. Dysnomia Makemake Eris Not Dwarf Planets Haumea

17. Eris and Dysnomia • - Discovered in 2003 • 67.7 AU from Sun • Eris is 2400 km in Diameter • (slightly larger than Pluto)

18. Eris Dysnomia

19. MakeMake – 46 AU 1900 Km in Diameter

20. Haumea – 43.1 AU 1400 km in dia Hi’iaka Namaka

21. Ceres • - Was the largest Asteroid • - 975 km in Diameter • 2.8 AU from Sun, in Asteroid belt • Not a “Plutoid”

22. Ceres