Astronomers using the Hubble Space Telescope discovered a fifth moon orbiting the icy dwarf planet Pluto in 2012. The tiny, new satellite - temporarily designated S/2011 (134340) 1 (and sometimes called P5) - was uncovered in a Hubble survey searching for potential hazards for the 2015 New Horizons spacecraft flyby of Pluto.
It is intriguing that such a small planet can have such a complex collection of satellites. The discovery provides additional clues for unraveling how the Pluto system formed and evolved. The favored theory is that all the moons are relics of a collision between Pluto and another large Kuiper belt object billions of years ago.
The moon is estimated to be 6 to 15 miles across. It is in a 58,000-mile-diameter circular orbit around Pluto that is assumed to be co-planar with the other satellites in the system.
S/2012 (134340) 1 was discovered on 26 June 2012 by a large team led by Mark Showalter using the Hubble Space Telescope.
How S/2011 (134340) 1 Got its Name:
S/2012 (134340) 1 was so designated because it is a satellite (S) that was discovered in 2012, and was the 1st satellite of dwarf planet Pluto (designated with its minor planet number (134340)) to be found that year. It is sometimes called P5 for brevity.