The Dwarf Planet Pluto http://en.wikipedia.org/wiki/Pluto

1. The Dwarf Planet Plutohttp://en.wikipedia.org/wiki/Pluto Dr. Harold Williams Montgomery College Planetarium http://Montgomerycollege.edu/Departments/planet/

2. Clyde Tombaughdiscover of Pluto

3. Lowell Observatory Astrograph

4. Lowell Observatory Blink Comparator

8. Ganymede (Jupiter), Titan (Saturn) and Callisto (Jupiter) Io (Jupiter), Luna (Earth), Europa (Jupiter), Triton (Neptune) and Pluto.

11. Asteroid Orbits • Most asteroids orbitin a belt between Mars and Jupiter • Trojan asteroids follow Jupiter’s orbit • Orbits of near-Earth asteroids cross Earth’s orbit

13. Wikipedia Links • http://en.wikipedia.org/wiki/Minor_planet • http://en.wikipedia.org/wiki/Minor_Planet_Center • http://en.wikipedia.org/wiki/Minor_planet_number • http://en.wikipedia.org/wiki/Eris_%28dwarf_planet%29 • http://en.wikipedia.org/wiki/Trans-Neptunian_object • http://en.wikipedia.org/wiki/Asteroid • http://en.wikipedia.org/wiki/List_of_asteroids_named_after_important_people

15. Only a tiny number of comets enter the inner solar system - most stay far from the Sun Oort cloud: On random orbits extending to about 50,000 AU Kuiper belt: On orderly orbits from 30-100 AU in disk of solar system

16. How big can a comet be?

17. Pluto’s Orbit • Pluto will never hit Neptune, even though their orbits cross, because of 3:2 orbital resonance • Neptune orbits three times during the time Pluto orbits twice

18. Is Pluto a Planet? • By far the smallest planet. • Not a gas giant like other outer planets. • Has an icy composition like a comet. • Has a very elliptical, inclined orbit. • Pluto has more in common with comets than with the eight major planets

19. Other Icy Bodies • There are many icy objects like Pluto on elliptical, inclined orbits beyond Neptune. • The largest of these, “Planet X” was discovered in summer 2005, is even larger than Pluto

20. Kuiper Belt Objects • These large, icy objects have orbits similar to the smaller objects in the Kuiper Belt that become short period comets • So are they very large comets or very small planets?

21. What are the large objects of the Kuiper belt like?

22. HST’s view of Pluto & Charon

23. What is Pluto like? • Its moon Charon is nearly as large as Pluto itself (probably made by a major impact) • Pluto is very cold (40 K) • Pluto has a thin nitrogen atmosphere that will refreeze onto the surface as Pluto’s orbit takes it farther from the Sun.

24. Other Kuiper Belt Objects • Most have been discovered very recently so little is known about them. • NASA’s New Horizons mission will study Pluto and a few other Kuiper Belt object in a planned flyby.

25. Is “Planet X” a planet?

26. Pluto and “Planet X” • Pluto’s size was overestimated after its discovery in 1930 • It was considered a planet, and nothing of similar size was discovered for several decades • Now other large objects have been discovered in Kuiper Belt, including “Planet X” • Some scientists consider all of those objects planets; others consider none of them planets.

27. Sedna in Green Circlehttp://en.wikipedia.org/wiki/90377_Sedna

29. What have we learned? • How big can a comet be? • The Kuiper belt from which comets come contains objects as large as Pluto. • What are the large objects of the Kuiper belt like? • Large objects in the Kuiper belt have orbits and icy compositions like those of comets. • Is “Planet X” a planet? • It remains a matter of opinion because scientists have not yet settled on a definition of the minimum size of a planet.

30. New Horizons Spacecraft • http://en.wikipedia.org/wiki/New_Horizons • Major Contractors JHU APL, SwRI • New Horizons NASA’s Pluto-Kuiper Belt Mission http://pluto.jhuapl.edu/

31. New Horizonslaunched January 19, 2006flyby Pluto July 14, 2015

32. Spacecraft New Horizons

33. Thermal Space Battery

34. Antennas of New Horizons (HGA, MGA and LGA)