Styx (moon)

Styx (formerly known as S/2012 (134340) 1 and informally as P5) is a small moon of the dwarf planet Pluto. It was discovered on June 26, 2012, using the Hubble Space Telescope. It is the fifth moon of Pluto discovered so far. The others are Charon, discovered in 1978, Nix and Hydra, which were discovered in 2005, and Kerberos, discovered in 2011.

 Discovery 
The moon was discovered using nine sets of images taken between 26 June and 9 July 2012 by Wide Field Camera 3 of the Hubble Space Telescope. NASA announced the discovery on 11 July 2012. The images were taken as part of a Hubble survey searching for potential hazards for the New Horizons mission, which went to Pluto in 2015. The discovery of the moon made scientists worried about the mission. Scientists working on New Horizons wanted it to pass just inside the orbit of Charon. However, Pluto may have had more bodies, such as dust or rings, orbiting it which cannot be found. These bodies could damage the New Horizons probe, and would mean that scientists had to change New Horizons' path so it would not be damaged.  On 1 July 2015, after looking for seven weeks, scientists found there were no other bodies around Pluto, and announced that New Horizons would stay on its original path. New Horizons was not damaged, and took a picture of Styx on 13 July 2015.

 Physical properties 
The moon is  across. Because of its small size, it is likely to be irregular in shape. The moon is very faint, about one one-hundred-thousandth as bright as Pluto. The moon is likely to be made of water ice.

 Orbital properties 
Styx orbits the centre of mass of Pluto and Charon at a distance of around . This is in between the orbits of Charon and Nix. The orbital path of the moon is very nearly circular, like the other moons of Pluto. The moon orbits in the same orbital plane as the other moons. The moon takes around 20 days to orbit Pluto.

 Origin 
The moon system around Pluto may exist because of a collision of Pluto with a large Kuiper belt body a very long time ago. Pluto’s moons may have formed from the scattered pieces of rock left behind after the collision.

 References 

Category:Pluto's moons