Until July 11, 2012, scientists believed Pluto had only four moons. However, thanks to images obtained with the Hubble telescope, it was possible to find another, fifth moon of this dwarf planet.
For several decades, only one satellite of Pluto was known - Charon, discovered back in 1978. Only in 2005 was it possible to discover two more moons of this small planet - Nikta and Hydra. Difficulties in the discovery and even more so in the study of Pluto's satellites arise not only because of its small size, but also because of the huge distance that separates it from the Earth. A detailed study of Pluto and its moons will be carried out only in 2015, when the NASA satellite reaches them.
In June 2011, the fourth satellite of Pluto was discovered, and in July 2012 - the fifth. The fifth moon was named P5 or S / 2012 (134340). At the moment, it is the smallest of Pluto's satellites known to astronomers: its diameter is about 10-25 km, although scientists have not yet been able to carry out calculations to find out the size of the satellite more accurately. Since the moon P5 is very small and located at a huge distance from the Earth, for a long time it could not be detected even with the most modern instruments. For comparison, the approximate diameter of Charon is 1200 km, which is 5-10 times larger than the currently established diameter of P5.
Even when Pluto's fifth moon appeared in images taken with the Hubble telescope, scientists were not immediately able to see it. Astronomer Mark Showalter required careful analysis of several images taken on June 26, 27 and 29, as well as July 7 and 9, 2012, to make sure that the tiny, barely visible dot on them is a celestial body that orbits Pluto. The discovery of the new moon was also facilitated by the fact that all of Pluto's satellites revolve around it in similar orbits. That is why scientists were able to take into account the data they already had about the four moons of Pluto in order to first detect the fifth, and then make sure that it is indeed a satellite.
