Pluto
While we have now addressed water on the major worlds and satellites, we don’t want to ignore the most recent discoveries of one of the most distant members of the solar system that we have just visited. The image at the top of the page is an artists impression of what the view from the surface of Pluto would look like. That fuzzy large star is our sun. With an average temperature of -223°C, it is pretty clear that the most likely form of water that we can expect to see on Pluto is ice. Its mass is tiny (0.0022 of Earth’s mass), so we don’t expect it capable of much internal activity (mantle convection, for example). And since Pluto is not circling a massive planet, tidal heating does not seem to be a good possibility. And so it was a surprise when the New Horizon mission returned images of what may be ice volcanoes on Pluto.
At the time that we put this course together, there was no good explanation for this. We don’t yet understand all possible heat sources that could account for this activity. We do think that the liquid erupting was not pure water but most likely some kind of slushy mixture of water, nitrogen, methane or ammonia.
We suggest you keep an eye on news releases related to this and we will simply conclude this section with this quote by Oliver White about those features on Pluto.
“"Whatever they are, they're definitely weird" — 'volcanoes' is the least weird hypothesis at the moment,"
