Gravity+and+Orbits

What will happen when you launch a cannonball off a mountain top that is above most of the atmosphere?


=[|click here to experiment with orbit of cannonball]=

Pluto is no longer considered a planet but is called a dwarf planet.
Scientists believe that Pluto was captured by the Sun. How did Pluto get its forward motion in the first place? What force keeps Pluto moving in circles and not flying off into space? Where does this force come from? List two factors that work together to keep Pluto and other planets in orbit around the sun.

[|Does gravity depend on the size of the planet?]