Located deep into the remote, cold depths of the outer solar system are the dwarf planets Pluto and Eris. For more the 60 years Pluto was considered the last of the planetary bodies of our solar system, but starting in 1992, it was discovered that it was but a member of a large swarm of objects orbiting the Sun beyond the orbit of Neptune, some of which have orbits that reach out more than 1000 AU's from the Sun! Pluto was considered the largest of these trans-Neptunian objects until Eris was discovered in 2003. It was this discovery that finally moved the International Astronomical Union to "demote" Pluto to the status of a "Dwarf Planet".
Below is an animation of Pluto made from images taken on June 10, 2007 and June 12, 2007.
Another animation of Pluto, this time made from images taken on June 14, 2009 and June 17, 2009.
Eris is located far beyond Pluto. The semi-major axis of its orbit is just under 68 AU, but the eccentricity is about 0.44, which means is retreats to well over 100 AU from the Sun at aphelion! Below is an animation from images made on June 16, 2007 and June 21, 2007. At the time, Eris was about magnitude 18.8 and nearly 97 AU from the Sun!
Another animation of Eris, this time made from images taken on June 14, 2009 and June 17, 2009. Eris is not easy to locate in the animation, but it is located just left of centre, above the double star.