Pluto

Pluto is a celestial body that orbits the Sun and lies in the outer region of the solar system. It was discovered in 1930 and was long classified as the ninth planet of the solar system. In 2006, the International Astronomical Union (IAU) issued a new definition, after which Pluto was reclassified as a 'dwarf planet'.

Pluto is part of a region of objects known as the Kuiper Belt, a vast zone filled with icy bodies and small rocky objects beyond Neptune's orbit. Its orbit is highly elliptical, and at certain times it comes closer to the Sun than Neptune does.

Discovery and naming

Pluto was first observed by Clyde Tombaugh, who worked at the Lowell Observatory in Arizona, United States. The search was motivated by calculations concerning an unseen body affecting the orbits of outer planets. The name 'Pluto' comes from the Roman god of the underworld. In Somali it is typically written as 'Buluuto'.

The 2006 redefinition

Between the 1990s and 2000s, other objects were discovered in the Kuiper Belt region that were similar in size to or larger than Pluto. This raised questions about the meaning of the term 'planet'. The 2006 IAU meeting defined three criteria: that the body orbits the Sun, that its gravity has given it a nearly round shape, and that it has cleared its orbital neighbourhood. Pluto failed to meet the third criterion, as it shares its orbit with other bodies.

Surface and moons

Pluto has moons, the largest of which is Charon. Charon is so large relative to Pluto that some scientists regard them as a binary system. Pluto's surface shows evidence of ice composed of nitrogen, methane, and carbon monoxide, and temperatures are extremely low.

Exploration

NASA's New Horizons spacecraft flew past Pluto and its surroundings in 2015, transmitting images and data that revealed a varied surface: icy mountains, plains, and a heart-shaped feature. These findings altered previous understanding of the geological activity of distant bodies.