Portal:Physics/Selected picture/August 2012

Discovery of Pluto's  fifth moon:

Hubble Space Telescope discovery of Styx, Pluto's fifth moon. (also informally known as P5) is a small natural satellite of Pluto whose discovery was announced on 11 July 2012. It is the fifth confirmed satellite of Pluto, and was found approximately one year after S/2011 (134340) 1 (or "P4"), Pluto's fourth discovered satellite. The moon is estimated to have a diameter of between 10 and 25 km, and orbital period of 20.2 ± 0.1 days.