Pluto surface ice

Pluto has vast plains of nitrogen, methane, and carbon monoxide ice, along with water ice mountains, revealed by the New Horizons spacecraft.

About this subject

Pluto's surface is dominated by volatile ices, primarily nitrogen, methane, and carbon monoxide, forming a dynamic and geologically active landscape. The most iconic feature is Sputnik Planitia, a vast nitrogen ice plain hundreds of kilometers across, located in the western hemisphere of the dwarf planet. This plain displays polygonal patterns from convective cells, indicating that nitrogen ice behaves as a viscous fluid over geological timescales, constantly refreshing the surface.

In addition to volatile ices, Pluto boasts water ice mountains that are more rigid, forming ridges and chains such as the Tenzing and Hillary mountains, with peaks up to 4 km high. Frozen water acts as the dwarf planet's rocky crust, supporting the terrain. The average surface temperature is about -230°C, but varies with altitude and solar exposure, causing sublimation and condensation of ices, which creates hazes and seasonal precipitation.

NASA's New Horizons mission, which flew by Pluto in July 2015, was crucial in revealing these details. Before the mission, Pluto was thought to be a geologically dead world covered by ancient ices, but images showed cryovolcanism, glacial flows, and a tenuous nitrogen atmosphere with pressure 100,000 times less than Earth's. The icy surface is constantly evolving, with methane ice deposits covering dark regions and changing the planet's color over time.

Frequently Asked Questions

What is the composition of the ice on Pluto's surface?

Pluto's surface is composed mainly of nitrogen, methane, and carbon monoxide ices. Water ice also exists, forming mountains and the dwarf planet's rigid crust.

Why does Pluto have nitrogen ice despite being so cold?

Nitrogen freezes at about -210°C, and Pluto's average temperature is -230°C, allowing it to exist as a solid. The low atmospheric pressure also facilitates sublimation and condensation of the ice.

How did the New Horizons spacecraft study Pluto's surface?

New Horizons flew by Pluto in 2015, using cameras and spectrometers to map the surface composition, topography, and temperature. The images revealed details such as Sputnik Planitia and the water ice mountains.