Pluto and its moons

Image of Pluto taken by the Hubble Space Telescope. When it was discovered in 1930 by an astronomer from the United States, Pluto was known as the smallest planet in the solar system and the ninth planet from the sun. Nowadays, it is referred to as a "dwarf planet." Like other planets, so-called dwarf planets orbit the sun but they are so small they are not able to clear other objects out of their paths.

The newest discoveries about Pluto add to the existing evidence testifying to what would be a very inhospitable environment for visiting explorers.

Image Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI), and the HST Pluto Companion Search Team

NASA's Hubble Space Telescope sent back news of a couple of new moons orbiting Pluto (which is at the center of the photograph.) You can make out the moon Charon slightly below Pluto. The new moons, Nix and Hydra, are to the right of Pluto and Charon.

Pluto, which orbits the sun in an oval pattern, is, on average, more than 3.6 billion miles away from the sun.

Icy Kuiper Belt objects orbit beyond Pluto and Neptune. The region is home to housands of small, icy objects like Pluto.

Temperatures on Pluto are believed to be 375 to 400 degrees below zero. The latest discover - after nearly two decades searching - posits that Pluto's atmosphere is filled with oisonous carbon monoxide gas.

NASA, ESA, A. Stern (Southwest Research Institute), H. Weaver (Johns Hopkins University/Applied Physics Lab), and the HST Pluto Companion Search Team

Pluto's atmosphere was previously known to extend more than 60 miles above the surface. New findings have now increased that height to more than 1,860 miles above the planet.

Pluto, the moon Charon, and two new satellites. Astronomers hope to learn more about Pluto when the New Horizons spacecraft, launched five years ago, arrives at Pluto in 2015.

NASA, ESA, and Southwest Research Institute

Views of Pluto's entire surface taken from multiple views photographed by the Hubble Space Telescope