Pluto: A Very Different Beast to Neptune's Moon Triton

Despite initial speculation that Pluto could be similar to Neptune’s moon Triton, early data from NASA’s New Horizons spacecraft shows Pluto is a different beast indeed.

Last year, a map was released of Triton showing the moon in its clearest detail yet. The map was based on Voyager 2 data when the spacecraft flew past the moon in 1989, as part of a larger solar system tour.

Produced by Paul Schenk at the Lunar and Planetary Institute in Houston, the map was made in part to compare Triton to Pluto. Both are bodies originating in the outer solar system, and it was thought there could be at least some similar features on them.

But as high-resolution data comes in slowly from New Horizons, winging its way out of the solar system, the surprise is just how little similarity there is, Schenk told Discovery News. Even the youngest features are very different between the two bodies.

“The central lesson here is that no two bodies in this part of the solar system are going to look alike or have the same geologic history,” Schenk said.

Scientists knew upfront there would be differences, to be sure. Triton is a fugitive of the outer solar system captured by Neptune long ago. The force of that gravitational capture melted vast plains on Triton’s surface, wiping away older craters and terrain.

Pluto, meanwhile, has been quietly orbiting in the outer solar system for billions of years and didn’t go through that kind of perturbation. So its terrain was already expected to be somewhat older, craggier and more cratered.

But there are mysteries that go beyond their different geologic histories, Schenk said. The youngest terrain on Pluto (Sputnik Planum) appears vastly different than young terrain on Triton. And there are mountains on Pluto that are hard to explain on a cold dwarf planet.

Beyond that, there’s a vast nitrogen ice sheet on its surface; how it got there and whether Triton (placed in the same spot as Pluto) could host such a phenomenon are open questions, Schenk explained.

Read more at Discovery News