7 New Things We've Just Learnt About Pluto

Data sent back by the New Horizons spacecraft, which flew by Pluto last year, is now giving us lots of new insights into the (dwarf) planet and its moons.

1. This is how Pluto and its moons orbit each other.

H.A. Weaver et al. / Science

That's Pluto in the middle and its largest moon Charon closest in, followed by Styx, Nix, Kerberos, and Hydra. You can see how Charon is big enough to actually pull Pluto about, meaning they both orbit a spot outside of Pluto.

As for the smaller, irregularly-shaped moons, we now know that Nix and Hydra are about 40km wide, and Styx and Kerberos are about 10km wide. All four of Pluto's small moons have highly reflective surfaces, suggesting they have water ice on their surfaces.

2. There's not much dust around the dwarf planet.

Bagenal et al. / Science

There are only six grains of dust per cubic mile of space around Pluto and its moons, according to data sent back from an instrument on board the New Horizon's spacecraft. That means that any left over planetary dust and debris from when the dwarf planet formed has all been swept up one way or another over the intervening years.

Scientists also saw that the solar wind (illustrated in the image above) – the flow of of protons and electrons continuously streaming from the sun at about 400 kilometres per second – is deflected around Pluto because of the dwarf planet's atmosphere.

3. It's atmosphere is colder and more compact than we thought.

NASA

Before New Horizons, we knew Pluto had an atmosphere but we didn't know all that much about it.

(Above is a picture of New Horizons incase you'd forgotten when it looked like).

4. There’s a haze all over the planet that goes all the way up to high altitudes.

Gladstone et al. / Science

You might recognise this photo as one of the first that came out shortly after the New Horizon's spacecraft passed by Pluto. Well, now scientists have done some science on it, and they've found that the haze that apparently surrounds Pluto has got lots of thin layers. It also has a bluish colour, which means it's probably made up of lots of very small particles.

5. Pluto is covered in lots of different types of terrain.

Moore et al / Science

Data from New Horizons suggests that Pluto's surface has changed a lot over the last few hundred million years, because of things like erosion. There's also evidence of tectonics and moving glaciers.

Craters on the planet range from 500m to 250km in diameter.

6. Some parts of Pluto's surface contain lots of red-brown molecules called tholins.

Grundy et al / Science / science.sciencemag.org

Fun fact: The term "tholins" was coined by Carl Sagan and his colleague Bishun Kahre to describe a class of molecules found in Saturn's moon Titan.

Pluto's surface also has lots of what planetary scientists call volatile ices, including water ice and solid nitrogen. According to one study published today they are distributed across the planet in a weird way thanks to geological activity.

7. There might be ICE VOLCANOES.

Moore et al / Science

Scientists have seen "tall mounds with central depressions" (see one in the picture above) on the surface of Pluto, which they think might be the result cryovolcanoes. Cryovolcanoes are volcanoes that spew ice instead of lava.