Pluto’s Heart Has Been Broken for Billions of Years
Billions of years ago, a piece of interplanetary debris smashed into Pluto and left an 825-kilometer-wide crater. But instead of turning into an ugly pockmark, that mighty scar may be responsible for one of Pluto’s most charismatic features: Its icy heart.
New data from NASA’s New Horizons spacecraft, which flew past Pluto in July, are helping scientists better understand the incredibly varied features on the world’s surface, which include smooth icy plains, parallel blades known as “snakeskin terrain,” and potential ice volcanoes.
Recently, observations revealed a circular feature surrounding the western ventricle of the striking, heart-shaped region known as Tombaugh Regio.
“The question is, could this be a relic giant impact basin?” asked Paul Schenk, at the 47th meeting of the American Astronomical Society’s Division for Planetary Sciences. “The key to that question is, is it deep? And the answer is yes.”
The basin is about 4 kilometers deep and stretches roughly one-third of the way across the icy world, said Schenk, of the Lunar and Planetary Science Institute. Finding a similarly sized gouge means going all the way to the other end of the solar system – to Mercury, where the Caloris impact basin stretches roughly one-third of the way across that roasted, dense world. (To put this in Earthly perspective, it would be as if a crater obliterated everything between Mexico and Canada, from California to North Carolina — aka, the majority of the United States.)
On Pluto, the smooth icefield known as Sputnik Planum sits within the basin. It’s a region that — unlike the possibly 4-billion-year old scar — is relatively young, at about 10 million years old. The edges of the basin are steep in the north but degraded in the south, where a large portion of the rim is missing. But the general shape is still obvious.
“It is indeed circular, except for the southern extension,” Schenk said. “The floor is basically flat.”
The impact created a depression that may have been perfect for accumulating flowing ices, especially given its location on the side of Pluto that never sees its large moon, Charon, said Douglas Hamilton of the University of Maryland, College Park. Pluto and Charon are locked in a whirling dance in which they keep the same face pointed at one another all the time. So Charon never fills the skies over Sputnik Planum – and none of the meager sunlight it reflects as Charonshine ever warms the cockles of Pluto’s heart.
That geometry helps make the region an efficient cold trap, or an area where ices can congregate. And that does seem to be what’s going on here. Will Grundy, from the Lowell Observatory, reported at the meeting that Sputnik Planum is full of basically every type of ice that has been spotted on Pluto, including carbon monoxide, nitrogen, and methane. The only species that’s conspicuously absent is water ice, which makes up the planet’s soaring mountains.
In fact, Sputnik Planum is more like an ice cap than anything else.
“We see ice caps throughout the solar system — ice caps on Earth, ice caps on Mars,” Hamilton said. “What we have to do is explain why this ice cap is at 30 degrees north on Pluto.”
It will take a bit of work to sort out exactly what happened, but scientists are well on their way to solving the mystery of Pluto’s heart.
Go Further
Animals
- Octopuses have a lot of secrets. Can you guess 8 of them?
- Animals
- Feature
Octopuses have a lot of secrets. Can you guess 8 of them? - This biologist and her rescue dog help protect bears in the AndesThis biologist and her rescue dog help protect bears in the Andes
- An octopus invited this writer into her tank—and her secret worldAn octopus invited this writer into her tank—and her secret world
- Peace-loving bonobos are more aggressive than we thoughtPeace-loving bonobos are more aggressive than we thought
Environment
- Listen to 30 years of climate change transformed into haunting musicListen to 30 years of climate change transformed into haunting music
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- U.S. plans to clean its drinking water. What does that mean?U.S. plans to clean its drinking water. What does that mean?
- Food systems: supporting the triangle of food security, Video Story
- Paid Content
Food systems: supporting the triangle of food security - Will we ever solve the mystery of the Mima mounds?Will we ever solve the mystery of the Mima mounds?
History & Culture
- Strange clues in a Maya temple reveal a fiery political dramaStrange clues in a Maya temple reveal a fiery political drama
- How technology is revealing secrets in these ancient scrollsHow technology is revealing secrets in these ancient scrolls
- Pilgrimages aren’t just spiritual anymore. They’re a workout.Pilgrimages aren’t just spiritual anymore. They’re a workout.
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- This ancient cure was just revived in a lab. Does it work?This ancient cure was just revived in a lab. Does it work?
Science
- The unexpected health benefits of Ozempic and MounjaroThe unexpected health benefits of Ozempic and Mounjaro
- Do you have an inner monologue? Here’s what it reveals about you.Do you have an inner monologue? Here’s what it reveals about you.
- Jupiter’s volcanic moon Io has been erupting for billions of yearsJupiter’s volcanic moon Io has been erupting for billions of years
- This 80-foot-long sea monster was the killer whale of its timeThis 80-foot-long sea monster was the killer whale of its time
Travel
- How to plan an epic summer trip to a national parkHow to plan an epic summer trip to a national park
- This town is the Alps' first European Capital of CultureThis town is the Alps' first European Capital of Culture
- This royal city lies in the shadow of Kuala LumpurThis royal city lies in the shadow of Kuala Lumpur
- This author tells the story of crypto-trading Mongolian nomadsThis author tells the story of crypto-trading Mongolian nomads