Pluto, which was classified a planet until the discovery of Elis in 2005, sits on the Kuiper belt near Neptune. In 2015, NASA’s New Horizons spacecraft performed a flyby of the space rock, where it snapped up an amazing photo of its atmosphere. However, it made a far more interesting discovery in the short time it stayed in orbit.
Brian Cox revealed during his BBC series “The Planets” why the space agency believes an ocean of water is hiding below the surface of Pluto.
He said last month: “By far the most recognisable feature is the reason known as Tombaugh Regio, or to give it its more popular name – Pluto’s heart.
“The western lobe of the heart is called Sputnik Planitia.
“A giant plain of frozen nitrogen, methane and carbon monoxide that stretches for a million square kilometres.
“And, at its edge, lies a range of mountains made of pure frozen water ice that rise up to 6km above the plain.
“But there’s something very strange about the region, something that sets it apart from the rest of this dwarf planet.”
Dr Cox went on to reveal how NASA noticed something particularly strange about this region.
He added: “The surface of Pluto is covered in craters, the scars of impact that have taken place over many billions of years.
“Except, if you look at Sputnik Planitia, it is absolutely smooth.
“There are no craters there, not a single one.
“Detailed imagery beamed back by New Horizons revealed a network of hexagon and pentagon shapes that crisscross the frozen nitrogen surface.
“A clue to what might be happening can be seen in the images.”
Dr Cox detailed how these patterns could suggest water is hiding below the surface of Pluto.
He continued: “These kind of patterns are found elsewhere in nature – on the surface of the Sun or in a liquid that has been heated from below – characteristics of convection.
“There’s a heat source that is causing material to rise up, then it cools and falls back again.
“That a small world like Pluto is still active was a huge surprise, our best theory of how this could be happening is that somewhere deep in its interior, there are radioactive elements that generate heat as they decay.
“This heat warms a sunless, half-frozen ocean of water that has existed for billions of years beneath the surface of Pluto.
“The evidence from Sputnik Planitia that there is still an internal heat source, and studies of other geological features, have led scientists to suggest that an ocean of water might still be there.”
Brian Cox revealed during the same series how another probe – Voyager – also made a surprising discovery near the planet Neptune.
He said during the same series: “Voyager 2 had almost completed its grand tour of the Solar System.”
He added: “When Voyager arrived, we saw geological activity on that frozen world, we saw geysers erupting up into space eight kilometres high.
“Then they carried dark material 100 kilometres downwind.
“Now the key to understanding what process caused those eruptions was that we noticed the geysers tended to erupt on a place on Triton’s surface below the faint Sun, even though it’s billions of miles away.
“What is happening in the sunlight is falling on the thin layer of nitrogen ice, going through and heating up a layer of darker particles a metre below the surface.”
