With the world set to have a view of Pluto later this year, DAVID ADAMS takes a look at what we know about the dwarf planet…
In July this year astronomers will get new insights into Pluto as the NASA spacecraft, New Horizons, completes a fly-by. Given that – and the fact that 18th February this year marked 85 years since its discovery – we thought it was time to take a closer look at what we know about the far-flung celestial body…
Artist’s concept of NASA’s New Horizons spacecraft as it passes Pluto and Pluto’s largest moon, Charon, in July 2015. PICTURE: NASA/JHU APL/SwRI/Steve Gribben
• Pluto was discovered in 1930 by American astronomer Clyde Tombaugh, who was working at the Lowell Observatory in Flagstaff, Arizona, in the US.
• It was named by 11-year-old Venetia Burney of Oxford in the UK after the Roman god of the underworld (and not the cartoon dog!) The moons – see below – also bear names associated with the mythological underworld.
• Pluto, which is believed to have a rocky core surrounded by a mantle of water ice, is located 7.3 billion kilometres from Earth and is part of a group of “objects” which sit beyond Neptune known as the Kuiper Belt.
• While long known as the solar system’s ninth planet (and early estimates put it at about the same size as Earth), Pluto is now thought to be considerably smaller with a diameter of only 2,302 kilometres (NASA says that if the sun were the size of a front door, the Earth would be the size of the US coin known as a nickel and Pluto would be the size of a pinhead). In line with its smaller-than-first-thought size, in 2006 Pluto’s status was changed from planet to that of a dwarf planet.
• Pluto has five known satellites – Charon, Nix, Hydra, Kerberos and Styx (Nix and Hydra were recently captured in images by New Horizons). Charon was discovered in 1978 and the rest much more recently: Styx, the last to be found, was only discovered in 2012 using the Hubble Telescope.
• Pluto and Charon are often referred to as a “double dwarf planet system” thanks to Charon’s size (about half that of Pluto) and both orbit around a point called the “barycenter”. Both bodies present the same face to each other and neither moves across the other’s sky.
• It takes Pluto 248 Earth-years to orbit the sun. A day on Pluto takes about 153 Earth-hours.
• Scientists do not think the icy Pluto could support life as we know it but some believe it may have an ocean hidden under its surface.
• The unmanned New Horizons spacecraft, the first sent on a mission to encounter the Pluto system, was launched in 2006 from Cape Canaveral in the US.
• On its journey to Pluto it has come up close to an asteroid and completed a fly-by of Jupiter. Its closest approach to Pluto will come on 14th July.
Sources: NASA, Space.com, New Horizons Mission, New Horizons
