Achi news desk-
A huge heart-shaped feature on Pluto’s surface has fascinated astronomers since NASA’s New Horizons spacecraft captured it in an image in 2015. Now, researchers think they’ve solved the mystery of how the distinctive heart came to be – and it could reveal new clues about the origin of the dwarf planet.
The feature is named Tombaugh Regio in honor of astronomer Clybe Tombaugh, who discovered Pluto in 1930. But the heart is not all one element, scientists say. And for decades, details on Tombaugh Regio’s elevation, geological composition and unique shape, as well as its highly reflective surface that is brighter white than the rest of Pluto, have defied explanation.
A deep basin called Sputnik Planitia, which forms the “left lobe” of the heart, is home to much of Pluto’s nitrogen ice.
The basin covers an area spanning 745 miles by 1,242 miles (1,200 kilometers by 2,000 kilometers), equivalent to about a quarter of the United States, but also 1.9 to 2.5 miles (3 to 4 kilometers) in lower in elevation than the majority of the planet’s surface. Meanwhile, the right side of the heart also has a layer of nitrogen ice, but it is much thinner.
Through new research on Sputnik Planitia, an international team of scientists has determined that a cataclysmic event created the heart. After analysis including numerical simulations, the researchers concluded that a planetary body about 435 miles (700 kilometers) in diameter, or about twice the size of Switzerland from east to west, is likely to collide with Pluto in early in the history of the dwarf planet.
The findings are part of a study about Pluto and its internal structure published on Monday in the journal Nature Astronomy.
Reconstructing an ancient ‘splat’ on Pluto
Previously, the team 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.
The researchers created the numerical simulations using smooth particle hydrodynamics software, considered the basis for a wide range of planetary collision studies, to model different scenarios for the impacts, speeds, angles and possible compositions of the collision of the hypothetical planetary body with Pluto.
The results showed that it is likely that the planetary body hit Pluto at an oblique angle, rather than on top of it.
“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 of the impact, and thanks to the angle of impact and the low speed, it did the core of the impact. it did not sink into the core of Pluto, but remained intact as a splat on it,” said the lead author of the study, Dr. Harry Ballantyne, research associate at the University of Bern in Switzerland, in a statement.
But what happened to the planetary body after it crashed into Pluto?
“Somewhere below Sputnik is the remnant of another giant body, which Pluto has never completely consumed,” study co-author Erik Asphaug, a professor at the University of Arizona’s Lunar and Planetary Laboratory, said in a statement.
The teardrop shape of Sputnik Planitia is a result of the frigidity of Pluto’s core, as well as the relatively low speed of the impact itself, the team discovered. Other types of faster and more direct effects would have created a more symmetrical shape.
“We are used to thinking of planetary collisions as very intense events where you can ignore the details except for things like energy, momentum and density. But in the distant Solar System, speeds are so much slower, and solid ice is strong, so you have to be much more precise in your calculations,” Asphaug said. “That’s where the fun begins.”
The New Horizons spacecraft captured an image of Pluto’s heart on July 14, 2015. (Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/NASA via CNN Newsource)
Pluto’s crazy origins
While studying the heart feature, the team also focused on Pluto’s internal structure. An impact early in Pluto’s history would have created a mass defect, causing Sputnik Planitia to slowly migrate towards the dwarf planet’s north pole over time while the planet was still forming. This is due to the fact that the basin is less massive than what surrounds it, in accordance with the laws of physics, the researchers explained in the study.
However, Sputnik Planitia is near the dwarf planet’s equator.
Previous research has suggested that Pluto may have a subsurface ocean, in which case the icy crust over the subsurface ocean would be thinner in the Sputnik Planitia region, creating a dense upwelling of liquid water and causing mass migration towards the equator, say the authors of the study.
But the new study offers a different explanation for the feature’s location.
“In our simulations, all of Pluto’s primordial mantle is excavated by the impact, and as the printer’s core material splatters onto Pluto’s core, it creates a local mass excess that may explain the equatorward migration without an ocean beneath the face, or at most a very thin one,” said co-author of the study Dr. Martin Jutzi, senior researcher of space research and planetary sciences at the Institute of Physics of the University of Bern.
Kelsi Singer, principal scientist at the Southwest Research Institute in Boulder, Colorado and co-deputy principal investigator on NASA’s New Horizons Mission, who was not involved in the study, said the authors did a thorough job of examining the modeling and develop their theories. , although he would have liked to see “a closer connection with the 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 show that the south is shallower than the north,” Singer said.
The researchers believe that the new theory about Pluto’s heart could shed more light on how the mysterious dwarf planet formed. Pluto’s origins have remained unclear given that it exists on the edge of the solar system and has only been closely studied by the New Horizons mission.
“Pluto is a vast wonderland of unique and fascinating geology, so more creative theories for explaining that geology are always useful,” Singer said. “What would help distinguish between different theories is more information about Pluto’s subsurface. We can only get that by sending a spacecraft to orbit Pluto, possibly with a radar that can look through the ice.”
