The ancient oceans of Pluto may have arisen relatively quickly after the now-frozen dwarf planet came to be, melting from ice in a process that suggests Pluto formed in just 30,000 years.
鈥淲e don鈥檛 really know how planets get assembled, but in general, we think things bang into each other, and they accumulate,鈥� says Francis Nimmo at the University of California, Santa Cruz, whose work was due to be presented at the聽cancelled Lunar and Planetary Science Conference in Texas.
Pluto probably had liquid water on its surface at some point: images from NASA鈥檚 New Horizons mission show giant rifts that were probably made as water froze and expanded. If Pluto had a 鈥渃old start鈥� and began as a mixture of rock and ice, its oceans would have come later as ice melted. If this were the case, there should be signs of earlier ice melting into oceans before later refreezing, but these haven鈥檛 been observed.
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This supports the idea that Pluto had a 鈥渉ot start鈥�, in which liquid water was present early on. Furthermore, Nimmo says that if Pluto鈥檚 oceans formed slowly, you would expect to see wrinkles on its surface. These haven鈥檛 been seen, suggesting they formed quickly.
Nimmo鈥檚 team modelled Pluto鈥檚 formation, accounting for how heat would travel through Pluto in either a hot or cold case. With a hot start, Pluto would have formed in less than 30,000 years, meaning it had oceans relatively soon after creation.
As Pluto鈥檚 core cooled, these oceans would have slowly refrozen. 鈥淚f this model is right, it suggests similar objects in the Kuiper Belt will聽have formed fast too, and that early oceans may have been pretty ubiquitous,鈥� says Nimmo.
