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For billions of years, Pluto and its largest moon Charon have been facing each other in a mutual tidal block. Since it is about half the size of Pluto, the moon and its planet are sometimes referred to as a double dwarf planet system, with speculation that they may share a common origin story. Now, scientists have understood how this unusual duo came to be, rotating as a single object before being separated into a binary pair.
Pluto and Charon may have formed through a “kiss and capture” mechanism, with the two icy bodies colliding and temporarily stuck together, spinning in a cosmic dance before separating into two objects that are still bound in orbit, according to a new newcomer. to study published in Nature Geoscience. “Most planetary collision scenarios are classified as ‘hit and run’ or ‘graze and merge’. What we discovered is something completely different – a ‘kiss and capture’ scenario where bodies collide , they meet briefly and then separate while remaining gravitationally bound,” said Adeene Denton, a NASA postdoctoral fellow and lead author of the study. in a statement.
Charon is the largest of Pluto’s five moons, stretching 754 miles (1,214 kilometers) while the dwarf planet itself measures 1,400 miles (2,253 km) across. For years, it was believed that Charon formed the same way as Earth’s Moon, through a massive collision. With the Earth-Moon system, however, the colliding bodies behaved more like fluids due to their larger sizes and the intense heat resulting from the collision. “Pluto and Charon are different – they are smaller, colder and made mainly of rock and ice. When we calculated the actual strength of these materials, we discovered something completely unexpected,” said Denton.
The researchers behind the study ran computer simulations of various collision scenarios and found that Pluto and Charon remained largely intact during their collision. They have merged together as a single object, oddly shaped, resembling a snowman, according to the model. After being entwined in an unbalanced rotation, the pair broke up and Charon, being the smaller of the two, was condemned to an almost circular orbit around Pluto.
“The compelling thing about this study is that the model parameters that work to capture Charon end up putting it in the right orbit,” Erik Asphaug, professor at the Lunar and Planetary Laboratory at the University of Arizona, and co-author. of the new study, he said in a statement. “You get two things right for the price of one.”
The study could also solve another mystery about Pluto, namely how the dwarf planet came to possess a theorized underground liquid ocean. As the two bodies separated from each other, according to the study, the collision process had caused a considerable amount of internal heat to be transferred into the two celestial objects. That internal heat may have caused Pluto to develop an ocean beneath the surface.
“We are particularly interested in understanding how this initial configuration affects Pluto’s geological evolution,” Denton said. “Heat from the impact and subsequent tidal forces may have played a crucial role in forming the features we see on Pluto’s surface today.”
The team plans to conduct follow-up studies to discover how tidal forces influenced the early evolution of Pluto and Charon when they were fused together, and how a similar process might have led to the creation of other binary systems.
