Scientists with the Space Telescope Science Institute (STSI) have discovered a small moon which is the fourth moon to be discovered circling Pluto. The new moon which is yet to be named is identified as P4 and joins Pluto’s other moons Charon, Nix and Hydra. First images of P4 were initially seen in 2006 but was more clearly seen and confirmed in July 2011.

Scientists were in fact searching for rings around the planet when they discovered the new moon. Mark Showalter of the SETI in Mount View, California who led the team mapping Pluto said in a statement that he finds it remarkable that the Hubble cameras enabled them to see such a tiny object so clearly from a distance of more than three billion miles away.

The discovery is a result of NASA’s $700 million New Horizons Mission which aims to send a probe into Pluto in 2015.

P4 is said to have a diameter of between eight to twenty miles while the biggest moon Charon which was discovered in 1978 has a diameter of 746 miles while the other moons Nix and Hydra discovered by Hubble images in 2005 both have a diameter between 20 and 70 miles.