Pluto has a ‘beating heart’ of frozen nitrogen that is doing strange things to its surface, scientists say

Mysterious world is 'completely different' from what we had expected

Pluto has a "beating heart" of frozen nitrogen that is doing strange things to its surface, Nasa has found.

The mysterious inside seems to be the cause of features on its surface that have fascinated scientists since they were spotted by Nasa's New Horizons mission.

"Before New Horizons, everyone thought Pluto was going to be a netball - completely flat, almost no diversity," said Tanguy Bertrand, an astrophysicist and planetary scientist at NASA's Ames Research Center and the lead author on the new study.

"But it's completely different. It has a lot of different landscapes and we are trying to understand what's going on there."

The new study helps illuminate the processes that have led to those different landscapes, and show how Pluto came to be such an unexpectedly interesting world.

The famous heart-shaped structure on Pluto became famous when New Horizons flew past and captured the romantic-looking feature on its surface. The structured, known as Tombaugh Regio, was one of the chief illustrations that Pluto wasn't the barren landscape that scientists had thought.

Such features appear to be formed because of the nitrogen heart on Pluto, the new study suggests. It also helps to demonstrate the similarities between Pluto and our own planet, showing the similarities and differences between the two worlds, sitting billions of miles away at the other end of the solar system.

Nitrogen gas is found everywhere in the air on Earth, but makes up most of Pluto's thin atmosphere. The rest includes traces of carbon monoxide and methane.

Frozen nitrogen also covers the surface, much of which is found in the heart shape. At day, the thin layer of ice warms and is turned into vapour; at night, it condenses and turns back into ice.

That functions like a heartbeat, pumping winds around the dwarf planet and changing its surface.

The new study suggests that the cycle pushes Pluto's atmosphere around in the opposite direction that it is spinning. That phenomenon is thought to be unique, and is called retro-rotation.

It also whips air near to the surface, pulling heat and material across the surface that create the distinctive patterns that can be seen on Pluto's surface, the researchers say.

"This highlights the fact that Pluto's atmosphere and winds - even if the density of the atmosphere is very low - can impact the surface," said Bertrand.