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- Scientists have long thought Pluto\u2019s moon Charon formed like Earth\u2019s moon<\/strong>, from molten material blasted out in a huge collision.<\/li>\n
- But a new study says the process might have worked differently for the Pluto-Charon system<\/strong>, which is much smaller and colder than Earth and its moon.<\/li>\n
- The researchers have instead put forward a \u2018kiss and capture\u2019 mechanism<\/strong>, where Charon would have collided with and stuck to Pluto before eventually separating.<\/li>\n<\/ul>\n
The University of Arizona published this original story on January 6, 2025. Edits by EarthSky.<\/p>\n
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\u2018Kiss and capture\u2019 could explain Pluto-Charon formation<\/h3>\n
For decades, scientists have theorized that Pluto\u2019s moon Charon formed through a process similar to Earth\u2019s moon. That is, two worlds smashed into each other, blasting out molten debris which eventually coalesced into a moon. But now, a new study from the University of Arizona has challenged this assumption. The revised version of events starts similarly, with a collision between two icy worlds billions of years ago. But rather than destroying each other, they may have spun together like a celestial snowman, before finally separating and remaining forever linked in orbit. <\/p>\n
By taking into account the structural strength of icy worlds, the researchers say they\u2019ve discovered an entirely new type of cosmic collision. They\u2019re calling it the \u2018kiss and capture\u2019 mechanism. <\/p>\n
They published the peer-reviewed study in the journal Nature Geoscience<\/em> on January 6, 2025.<\/p>\n
Pluto and Charon NOT like our Earth and moon<\/h3>\n
Scientists\u2019 theory for how the Earth-moon system formed relies on the immense heat and huge masses involved. This would have made the colliding bodies behave like fluids, allowing our moon to form from ejected molten material. But this may not be true when applied to the smaller, colder Pluto-Charon system. The new study argues that scientists may have overlooked a crucial factor: the structural integrity of rock and ice.<\/p>\n
Adeene Denton, the study\u2019s lead author, explained:<\/p>\n
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Pluto and Charon are different \u2013 they\u2019re smaller, colder and made primarily of rock and ice. When we accounted for the actual strength of these materials, we discovered something completely unexpected.<\/p>\n<\/blockquote>\n
![\"Round](\"https:\/\/earthsky.org\/upl\/2022\/09\/Charon-red-cap-New-Horizons-2015-2.jpg\")
View larger. | Pluto\u2019s largest moon, Charon. NASA\u2019s New Horizons spacecraft took this image during its Pluto flyby in 2015. Image via NASA\/ JHUAPL\/ SwRI.<\/figcaption><\/figure>\n Hit and run, graze and merge \u2026 or kiss and capture?<\/h3>\n
The researchers ran impact simulations on the University of Arizona\u2019s high-performance computing cluster. And they found that, instead of stretching like silly putty during the collision, Pluto and the proto-Charon may have become temporarily stuck together. They would have then rotated as a single snowman-shaped object before separating into the binary system we observe today. A binary system occurs when two celestial bodies orbit around a common center of mass, much like two figure skaters spinning while holding hands. <\/p>\n
Denton said:<\/p>\n
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Most planetary collision scenarios are classified as \u2018hit and run\u2019 or \u2018graze and merge.\u2019 What we\u2019ve discovered is something entirely different: a \u2018kiss and capture\u2019 scenario where the bodies collide, stick together briefly and then separate while remaining gravitationally bound.<\/p>\n<\/blockquote>\n
Senior study author Erik Asphaug added:<\/p>\n
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The compelling thing about this study, is that the model parameters that work to capture Charon end up putting it in the right orbit. You get two things right for the price of one.<\/p>\n<\/blockquote>\n
- But a new study says the process might have worked differently for the Pluto-Charon system<\/strong>, which is much smaller and colder than Earth and its moon.<\/li>\n