The distinctive mark on Pluto's surface that resembles a heart was most likely caused by its collision with another celestial body. It happened when the dwarf planet was still young. The unusual manner of the collision explains the structure's seemingly impossible shape and location.
Pluto, a dwarf planet located at the edge of the solar system, holds many secrets. One of the most interesting things has to do with the distinctive heart-shaped pattern on its surface. Scientists from the University of Bern and the University of Arizona decided to take a closer look at this structure, which is scientifically called Tombo Reggio, and how it might have formed.
Slow collision
The authors of the article, which appears in the journal Nature Astronomy, note that the shape of the western part of the core, also called Sputnik Planitia, resembles an unusual impact crater. This region is slightly lower than the rest of Pluto's surface. The researchers modeled collisions between Pluto and a hypothetical impactor until they obtained a crater with parameters consistent with the body.
Simulations showed that Pluto could collide with a celestial body with a diameter of more than 640 kilometers. The impact occurred at a shallow angle and at a relatively low speed, which explains Sputnik Planitia's unusually elongated shape. As scientists have shown, such a massive impact may have occurred very early in the dwarf planet's history.
– Pluto's core is so cold that its rocks did not melt despite the heat released during the collision, and the meteorite's core did not penetrate the planet's core, but remained there as a spot – explained Harry Ballantyne from the University of Bern, lead author of the study.
Pluto. Tombaugh Regio can be seen on the right. Sputnik Planitia is its left halfNASA/Johns Hopkins University Applied Physics Laboratory/Southwestern Research Institute
Unnecessary surroundings
The study also sheds new light on Pluto's internal structure. According to the laws of physics, a giant depression like Sputnik Planitia should move towards the dwarf planet's pole over time, rather than staying close to the equator – this is due to its thin structure and therefore low mass compared to its surroundings. Scientists tried to explain this anomaly by the presence of an underground ocean of liquid water, which would push the “heart” upward and prevent it from moving. The new study offers an alternative explanation, which is that the additional mass preventing the migration may come from the flattened impact body at Pluto's core.
“We have discovered entirely new possibilities for the evolution of Pluto that may also apply to other Kuiper Belt objects,” said Adeniy Denton of the University of Arizona, who co-authored the paper.
University of Arizona
Main image source: NASA/Johns Hopkins University Applied Physics Laboratory/Southwestern Research Institute
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