Pluto's moons tumble in orbit, Hubble measurements reveal

Analysis of ten years of data from the space telescope has revealed the unusual trajectories, and also suggests Pluto might in fact be a binary dwarf planet

Pluto's moons have been tracked closely for the first time, showing that they tumble unpredictably rather than keeping one face fixed on their host planet.

Astronomers also observed that Pluto, whose status was downgraded to a dwarf planet in 2006, might be better regarded as a binary dwarf as it is locked in orbit with its largest moon, called Charon.