2024-04-19 06:11:00
(CNN) — A huge heart shape on the surface of Pluto has fascinated astronomers since NASA’s New Horizons spacecraft captured it in a 2015 image. Now scientists believe they have solved the mystery of how the distinctive heart formed, which could reveal new clues about its origins. the dwarf planet.
The feature is called Tombaugh Regio after the astronomer Clybe Tombaugh, who discovered Pluto in 1930. But the heart is not a whole element, scientists say. And for decades, details about Tombaugh Regio’s height, geological composition and distinctive shape, as well as its brighter white, highly reflective surface than the rest of Pluto, have defied explanation.
A deep basin called Sputnik Planitia, which makes up the “left lobe” of the heart, houses much of Pluto’s nitrogen ice.
The basin covers an area of 1,200 kilometers by 2,000 kilometers, equivalent to a quarter of the United States, but is also 3 to 4 kilometers lower than most of the planet’s surface. Meanwhile, the right side of the heart also has a layer of nitrogen ice, but it is much thinner.
The New Horizons spacecraft captured an image of the heart of Pluto on July 14, 2015. (Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/NASA)
Through new research on Sputnik Planitia, an international team of scientists has determined that a cataclysmic event created the heart. After an analysis that included numerical simulations, the researchers concluded that a planetary body about 700 kilometers in diameter, or roughly twice the size of Switzerland from east to west, likely collided with Pluto early in the planet’s history.
The findings are part of a study on Pluto and its internal structure published this Monday in the journal Nature Astronomy.
Recreation of an ancient “splash” on Pluto
Previously, the team had studied unusual features across the Solar System, such as those on the far side of the Moon, which were likely created by collisions during the chaotic early days of the system’s formation.
Scientists created the numerical simulations using smoothed particle hydrodynamics software, considered the basis for a wide range of planetary collision studies, to model different scenarios of potential impacts, speeds, angles and compositions of the theorized planetary body collision with Pluto.
The results showed that the planetary body likely collided with Pluto at an oblique angle, rather than head-on.
“Pluto’s core is so cold that (the rocky body that collided with the dwarf planet) remained very hard and did not melt despite the heat from the impact, and thanks to the impact angle and the low speed, the core of the impactor did not sink into Pluto’s core, but remained intact as a splash over it,” lead study author Dr. Harry Ballantyne, a researcher at the University of Bern in Switzerland, said in a statement.
But what happened to the planetary body after colliding with Pluto?
“Somewhere beneath Sputnik is the remaining core of another massive body, which Pluto never fully digested,” Erik Asphaug, co-author of the study and a professor at the University of Arizona’s Lunar and Planetary Laboratory, said in a statement.
The team discovered that Sputnik Planitia’s teardrop shape is due to the frigidity of Pluto’s core and the relatively slow speed of the impact. Other types of faster and more direct impacts would have created a more symmetrical shape.
“We are used to thinking of planetary collisions as incredibly intense events where the details can be ignored except for things like energy, momentum and density. But in the distant solar system the velocities are much lower and the ice is strong, so you have to be much more precise in your calculations yours, Asphaug explains, “That’s where the fun begins.”
The sinister origins of Pluto
While studying heart function, the team also focused on Pluto’s internal structure. An impact early in Pluto’s history would have created a mass deficit, causing Sputnik Planitia to slowly migrate toward the dwarf planet’s north pole over time, while the planet was still forming. This is because the pool is less massive than its surroundings, according to the laws of physics, the researchers explain in the study.
However, Sputnik Planitia is close to the dwarf planet’s equator.
Previous research has suggested that Pluto could have a subsurface ocean, in which case the icy crust above the ocean floor would be thinner in the Sputnik Planitia region, creating a dense bulge of liquid water and causing mass migration toward the equator, the authors noted.
However, the new study offers a different explanation for the location of this trait.
“In our simulations, Pluto’s entire early mantle is excavated by the impact, and as core material from the impactor spurts into Pluto’s core, a local excess mass is formed that could account for its equatorward migration without a subsurface ocean, or at most a very thin hav. one,” said study co-author Dr. Martin Jutzi, senior researcher for space and planetary sciences at the Department of Physics at the University of Bern.
Kelsi Singer, a senior scientist at the Southwest Research Institute in Boulder, Colorado, and deputy director of NASA’s New Horizons mission, who was not involved in the study, said the authors did a thorough job exploring the modeling and developing their hypotheses. although he would like to see “a closer link with geological evidence”.
“For example, the authors suggest that the southern part of Sputnik Planitia is very deep, but much of the geological evidence has been interpreted to mean that the south is shallower than the north,” Singer said.
Scientists believe the new theory about Pluto’s heart may shed more light on how the mysterious dwarf planet formed. Pluto’s origins have remained unclear since it exists on the edge of the solar system and has only been carefully studied by the New Horizons mission.
“Pluto is a big wonderland with unique and fascinating geology, so more creative hypotheses to explain geology are always useful,” says Singer. “What will help distinguish between the different hypotheses is more information about Pluto’s subsurface. We can only get that by sending a space mission to orbit Pluto, potentially with radar that can peer through the ice.”
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