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

Clyde Tombaugh discover of Pluto

Lowell Observatory Astrograph

Lowell Observatory Blink Comparator

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

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

http://en.wikipedia.org/wiki/Minor_planet

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

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

How big can a comet be?

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

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

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

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?

What are the large objects of the Kuiper belt like?

HST’s view of Pluto & Charon

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.

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.

Is “Planet X” a planet?

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.

Sedna in Green Circle http://en.wikipedia.org/wiki/90377_Sedna

90377 Sedna is a trans-Neptunian object, discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, 2003. 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 http://en.wikipedia.org/wiki/90377_Sedna

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.

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/

New Horizons launched January 19, 2006 flyby Pluto July 14, 2015 http://en.wikipedia.org/wiki/New_Horizons

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.

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. http://www.journalnet.com/articles/2003/12/16/news/local/news02.txt Single radioisotope thermoelectric generator, or RTG, supplied by the Department of Energy.

Antennas of New Horizons (HGA, MGA and LGA)