1. The Dwarf Planet Pluto http://en.wikipedia.org/wiki/Pluto
Dr. Harold Williams
Montgomery College Planetarium

2. Clyde Tombaugh discover 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 orbit in 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

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 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 Circle http://en.wikipedia.org/wiki/90377_Sedna

28. 90377 Sedna is a trans-Neptunian object, discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, At the time of its discovery it was the most distant observed natural solar system body. Sedna may qualify as a dwarf planet pending the detailed definition of that category by the International Astronomical Union. From

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
Major Contractors JHU APL, SwRI
New Horizons NASA’s Pluto-Kuiper Belt Mission

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

32. Spacecraft New Horizons
In the clean room at KSC’s Payload Hazardous Servicing Facility, technicians prepare the New Horizons spacecraft for a media event. Photographers and reporters will be able to photograph the New Horizons spacecraft and talk with project management and test team members from NASA and the Johns Hopkins University Applied Physics Laboratory.
The RTG seen in this picture is not the real flying unit and is only a mockup. The real RTG was installed shortly before launch.

33. Thermal Space Battery
The thermal space battery being developed at Argonne National Laboratory-West will help NASA discover if water exists on the moons of Jupiter. This photo is a press release photo courtesy of Argonne National Laboratory-West.
Single radioisotope thermoelectric generator, or RTG, supplied by the Department of Energy.

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