S/2012 P 1 (also known as S/2012 (134340) 1 or P5) is a small natural satellite of Pluto whose existence was announced on 11 July 2012. It is the fifth satellite of Pluto to be confirmed, and was found approximately one year after S/2011 P 1, Pluto's fourth discovered moon.

Discovery

The moon was discovered using nine sets of images taken between 26 June and 9 July 2012 by the Wide Field Camera 3 fitted to the Hubble Space Telescope. The survey work leading to the moon's discovery was in preparation for the arrival of the New Horizons space probe, currently en route to the Pluto system.

The discovery of a new, small moon led to concerns that the region of space may harbor many more bodies that are too small to be detected, raising fears that the probe may be damaged by an uncharted body as it passes through the system. It is speculated that the unexpectedly complex moon system around Pluto is the result of a collision between Pluto and another Kuiper belt object in the distant past.

Physical characteristics

The moon is estimated to have a diameter of between 10 and 25 kilometers (6 and 16 mi). These figures are inferred from the apparent magnitude of the moon and by using an estimated albedo of 0.35 and 0.04 for the lower and upper bounds respectively.

S/2012 P 1's orbital period is estimated to be 20.2 +/- 0.1 days, putting it about 5.4% from a 1:3 resonance with the Charon–Pluto orbital period. With Pluto's other moons Nix, S/2011 P 1 and Hydra, it forms part of a 1:3:4:5:6 sequence of near resonances.

Salient Features
Discovery
Discovered by Showalter, M. R. et al.
Discovery date 26 June 2012 (verified 7 July 2012)
Detection method Photographic

Orbital characteristics
Mean orbit radius 42,000 km (26,000 mi) +/- 2,000 km (1,200 mi)
Eccentricity ≈ 0
Orbital period 20.2 +/- 0.1 days
Inclination ≈ 0
Satellite of Pluto

Physical characteristics
Mean radius 5–12.5 km (3–8 mi)