Pluto is the smallest, coldest and outermost planet in the Solar System. It was the last to be discovered, identified in 1930 by the American astronomer Clyde Tombaugh. He compared photographs of part of the sky taken six days apart and noticed that a pinprick of light had moved slightly against the background of stars. Pluto was the only outer planet not visited by Voyager 2, so astronomers still know little about it. Some even propose that Pluto is really a comet and not a planet at all.

Pluto has a very elongated orbit, ranging between 7400 and 4400 million kilometres from the Sun, bringing it inside the orbit of Neptune for part of the journey. Pluto’s moon, Charon, is just over half its size and lies only 19,640 kilometres away from it. Both spin in a direction opposite to that of the other planets except Venus.

Pluto is denser than the icy moons of Uranus and Neptune, suggesting that it has relatively large, rocky core.

Pluto’s surface is probably an “icescape” of frozen nitrogen, carbon monoxide and methane. There may be craters made by collisions with rock and ice fragments. Seen from Pluto, the Sun looks no more than a bright, distant star. It still provides just enough heat to evaporate some of the surface frost and create an extremely thin atmosphere. Charon, Pluto’s nearby moon, features prominently in the sky.

Thousands of icy objects may exist in the outer reaches of the Solar System. They may form either a belt or a cloud. This could be the birthplace of comets.

Picture Credit : Google