Styx (moon)
Styx (formerly known as S/2012 (134340) 1 and informally as P5) is a small moon of the dwarf planet Pluto.[1][3] It was discovered on June 26, 2012, using the Hubble Space Telescope.[1] It is the fifth moon of Pluto discovered so far.[3][4][5] The others are Charon, discovered in 1978, Nix and Hydra, which were discovered in 2005, and Kerberos, discovered in 2011.
.jpg) Styx as seen in 2015 by New Horizons | |
| Discovery | |
|---|---|
| Discovered by | Showalter, M. R. and others[1] |
| Discovery date |
|
| Photographic[1] | |
| Orbital characteristics | |
Mean orbit radius | 46,500 km (28,900 mi)[2] |
| Eccentricity | ≈ 0 |
| 20.2 ± 0.1 days | |
| Inclination | ≈ 0 |
| Satellite of | Pluto |
| Physical characteristics | |
Mean radius | 10–24 km (6–15 mi)[2] |
| 27 ± 0.3 | |
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.[6] 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.[1][6] 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.[4] 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.[7] New Horizons was not damaged, and took a picture of Styx on 13 July 2015.
Physical properties
The moon is 10 to 24 km (6.2 to 14.9 mi) across.[2][3][4] Because of its small size, it is likely to be irregular in shape.[3] The moon is very faint, about one one-hundred-thousandth as bright as Pluto.[5] The moon is likely to be made of water ice.[8]
Orbital properties
Styx orbits the centre of mass of Pluto and Charon at a distance of around 46,500 km (28,900 mi).[2][9] 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.[1][4] The moon takes around 20 days to orbit Pluto.[9]
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.[1][3][5] Pluto’s moons may have formed from the scattered pieces of rock left behind after the collision.[5]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 "S/2012 (134340) 1 (P5): Overview". NASA. Archived from the original on 2015-07-05. Retrieved 2012-09-02.
- ↑ 2.0 2.1 2.2 2.3 "Styx". NASA. Retrieved 2025-11-15.
- ↑ 3.0 3.1 3.2 3.3 3.4 "Hubble discovers new Pluto moon". BBC. 2012-07-11. Retrieved 2012-07-28.
- ↑ 4.0 4.1 4.2 4.3 "Fifth moon is cold comfort for Pluto", New Scientist, Reed Business Information Ltd, no. 2874, p. 11, 2012-07-21
- ↑ 5.0 5.1 5.2 5.3 "New Moon for Pluto: Hubble Telescope Spots a 5th Plutonian Satellite". Scientific American. 2012-07-11. Retrieved 2012-07-28.
- ↑ 6.0 6.1 "Hubble Discovers a Fifth Moon Orbiting Pluto". NASA. 2012-07-11. Retrieved 2012-07-28.
- ↑ "NASA's New Horizons Spacecraft Stays the Course to Pluto". NASA. 2025-07-01. Retrieved 2025-11-15.
- ↑ "Astronomy Picture of the Day - 16 July 2012". NASA. Retrieved 2012-07-28.
- ↑ 9.0 9.1 "Hubble Space Telescope detects fifth moon of Pluto (Update)". Phys.Org. 2012-07-11. Retrieved 2012-07-28.