So you want to go to Pluto? Astronomy PHY 6323 October 2004 Presented by Margaret Milligan

Pluto and Charon History Exsistance of Pluto was predicted by Lowell in 1919 – affectionately called “Planet X” Pluto was finally discovered in 1930 by Clyde W Tombaugh. Named after the Roman God of the Underworld. Charon discovered in 1978 by Jim Christy. Named after the mythological figure that ferried the dead across River Acheron into Hades (the Underworld) Pluto Charon Tombaugh

Why should I go to Pluto? “Misfit Planet” – does not follow trends of outer planets. Unique orbit – crosses path of Neptune Unique spin – tilt is about 124 ° from normal Smallest planet – diameter is about equal to distance from New York to Las Vegas Completely full moons (of Charon) are only seen at beginning of spring and fall and full cycle is only 6.4 days!

What is Pluto? Composition of Pluto –Based on density of 2 grams/cm 3 it is believed that Pluto is mixture of ice and rock, but actual composition is unknown. –Pluto is a mixture of surface ices surrounding a water and ice mixture. The center of Pluto is rock. –Inner planets are rocky planets while outer planets are gaseous. Pluto is a misfit. Composition of Charon –A mixture of water and rock with surface ices.

Where is Pluto? Pluto is usually the ninth planet in our solar system Closest distance to sun is AU. This was last reached on Sept. 5, 1989 (perihelion). From Feb. 7, 1979 until Feb. 11, 1999 Pluto was the eighth planet since it was closer to the sun than Neptune. The furthest distance between Pluto and the Sun is 44.6 AU (aphelion).

Information about Pluto Radius: 1,145 to 1,200 km g on Pluto surface: 0.58 m/s 2 Mass of Pluto: 1.3 x kilograms Density: 2 grams/cm 3 Surface Composition: H 2 O, N 2, CH 4, CO ices Atmospheric Composition: N 2, CH 4, CO Surface Temp: 40 Kelvin (-233°C) Spin period: 6.39 Earth days (this is equal to spin of Charon) Orbital period of Pluto: 248 years Average distance from sun: 39.5 AU Closest: AU Furthest: 44.6 AU Inclination of orbit: 17°

What should I see while on Pluto? The length of Pluto’s day is the same as Charon’s orbital period. By the time that we reach Pluto around 2010, the phases of Charon will appear as below. The sun will be 35° north latitude. This is vastly different than the phases that would have been seen in The sun would have been 53 ° south latitude.

How do I get to Pluto? New Horizons – A Pluto-Kuiper Belt Mission Scheduled to launch in January 2006 and should reach Pluto and Charon by Mission to study surface properties, geology, interior makeup, and atmospheres. The mission will swing past Jupiter (to use its gravity to sling shot outward) and rendezvous with Pluto in 2015 and continue to move outward into the Kuiper Belt. Budget concerns may ground the mission. Mission Trajectory

Online References es/ast17feb99_1.htmhttp://science.nasa.gov/newhome/headlin es/ast17feb99_1.htm ts/plutopage.htmlhttp://nssdc.gsfc.nasa.gov/planetary/plane ts/plutopage.html