Pluto

Pluto, is the second largest Dwarf Planet after Eris. It used to be a planet, but now it is known as a Dwarf Planet.

Overview
working at the Lowell Observatory in Flagstaff, Arizona. Tombaugh discovered Pluto accidentally while looking for an unknown planet called Planet X that was causing disturbances in the orbits of Uranus and Neptune. By comparing two photographs of the night sky taken one week apart, he noticed an unknown faint spot that had possibly moved. Photographs obtained later confirmed the moving object and after receiving suggestions for the new planet’s name from around the world, the name Pluto was announced on May 1, 1930. Later observations of Pluto however showed that it was not the Planet X that astronomers were looking for. In fact, it was later shown that Planet X did not really exist.

looking for. In fact, it was later shown that Planet X did not really exist.

Pluto lies within a disc-shaped zone beyond Neptune’s orbit populated by tiny icy objects. This region is called the Kuiper Belt and its inhabitants are referred to as Kuiper Belt objects or trans-Neptunian objects. But in recognition of Pluto’s special place in astronomical history when it was downgraded to a dwarf planet, objects found in this region are also called “plutoids”. This icy region is believed to have formed in the early evolution of the Solar System. Not all plutoids are tiny. Eris, another dwarf planet, is actually more massive than Pluto. Because of its distance, it is difficult to determine what Pluto is made of. But it is believed to be composed of a rocky core, a mantle of water ice and a surface covered with methane ice and frosty nitrogen.

looking for. In fact, it was later shown that Planet X did not exist.