Pluto's new moon

Another moon has been discovered orbiting the dwarf planet Pluto. This is the planet's fifth known satellite, and it was spotted by astronomers using the Hubble Space Telescope.

Visible as a tiny speck of light in the image below, the moon – designated simply P5 – is estimated to be between 10 and 25km (6-15 miles) across. For comparison, Pluto’s largest moon, Charon, has a diameter of over 1,200km, and our own Moon’s diameter is about 3,500km.

Pluto’s collection of moons is surprisingly complex for such a small planet. It’s thought that this moon system was formed from a collision between Pluto and another Kuiper belt object billions of years ago.

Understanding more about this system is important for the planning of future missions to the edge of the Solar System. In 2015, NASA’s New Horizons spacecraft will make a historic flyby of Pluto, providing the closest ever glimpse of this icy planet. Scientists will be keeping tabs on Pluto’s satellites so that they can steer the spacecraft on a safe trajectory through this minefield of moons.

Related reading:

What drew Pluto into the Solar System?
Could Neptune and Pluto ever collide, as their orbits intersect?