Hubble’s still turning up surprises, even today. Whilst focusing her gaze at Pluto, doing some extra research in preparation for the New Horizons flyby in 2015, Hubble has found an extra blob in its vicinity. That’s right Pluto has a new moon.
Pluto already has 3 moons. Charon is the biggest at over 1000km across and is the largest moon in the solar system when compared to the size of its companion, Pluto. There’s also Nix, Hydra and now P4, although that isn’t it’s official name just a nickname for the time being.
The new moon could be between about 10-40km across, making it Pluto’s smallest moon. It’s difficult to judge its size initially. It’s probably a very icy body, like most things out this far – 5.9 billion km – meaning that it’d have a fairly icy surface. If this is the case the moon reflects a lot of the light from Sun and that’ll mean it’d be on the smaller side of things. If it’s reflecting a small amount of light though, meaning it’s a darker body (this could be due to radiation effects) then it’d be on the larger side of things.
P4 fits nicely between the orbits of Nix and Hydra. It’s thought that the moons were created in a large impact event much like the theory behind our own moons formation where a large body hit the planet, flung material into space and then re-coalesced to form the moon.
We’ll be finding out more about this intriguing, unexplored part of the Solar System when New Horizons flies by in 4 years time. It’s a pretty exciting mission where we’ll be looking in detail at Kuiper Belt Objects for the first time.