Glossary term: Pluto

Description: Pluto is one of the celestial bodies in our Solar System. It is located in the Kuiper Belt, beyond the orbit of Neptune. It used to be known as the ninth Solar System planet, but in 2006 it was reclassified as a dwarf planet. It was discovered in 1930 by Clyde Tombaugh. NASA's New Horizon mission was the first spacecraft to fly by Pluto, in 2015, and found that it has the following properties: Its average distance from the Sun is 6 billion kilometers (km), its radius is 1185 km (smaller than the Earth's moon), and hydrogen gas covers a large area of ​​its very cold surface. Its atmosphere extends to a distance of 1600 km. Its year is equivalent to 247.9 Earth years and its day is equivalent to 6.4 Earth days. Pluto is composed of rocks (70%) and ice (30%). It has five known moons: Charon, Styx, Nix, Kerberos, and Hydra.

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The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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Image of Pluto in enhanced colour to bring out differences in surface composition. They include craters, ridges and plains.


Caption: NASA's New Horizons spacecraft captured this high-resolution enhanced colour view of the dwarf planet Pluto on in July 2015. The image combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC). Pluto’s surface appears enhanced in this view to a rainbow of pale blues, yellows, oranges, and deep reds. The image resolves details and colours on scales as small as 1.3 kilometers.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute credit link
License: PD Public Domain icons