José Manuel NievesSEGUIRMadrid Updated: Save Send news by mail electrónicoTu name *
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Pluto is, at present, one of the planets coldest in the Solar System. In fact, since its surface in the distant Kuiper belt, the Sun looks like a small ball of orange, just something that is brighter than the other stars. And until now, scientists thought that the origin of the dwarf planet should be very cold.
But recently more than a year, the probe New Horizons , which looks closely at Pluto and its moons, and found evidence that under its icy surface is a vast ocean of liquid water. One whose depth can reach up to 150 km, and that gives wings to even the possibility that there could be life.
Now, a team of researchers from the University of California at Santa Cruz, has just published a paper in Nature Geosciences that explains that, after all, Pluto was able to have a “source” hot. According to scientists, the accumulation of new materials during the planet formation could, in effect, have generated sufficient heat to create, almost from the beginning, a large ocean of liquid water able to endure until our days under the frozen crust, even in spite of the distance of the Sun.
The idea was opposed outright to the former belief that Pluto started as a dense ball of ice and rock, and the ocean interior should its existence to the heat generated by the decay of radioactive elements in the rocks.
“For a long time -says Francis Nimmo, a co-author of the study – people will have questions about the thermal evolution of Pluto and the capacity of the ocean underground to survive until our days. Now that we have images of the surface of Pluto mission New Horizons of the NASA, we can compare what we see with what we predict the different models of thermal evolution”.
According to Carver Bierson, first author of the research, given that water expands when it freezes and contracts when it melts, the different scenarios of formation of hot or cold have different implications for the tectonics and the characteristics of the resulting surface of Pluto.
“If the beginning was cold -explains the researcher – and the ice melted internally, Pluto would have collapsed, and we should be able to see traces of compression in its surface, while if the source was hot the planet would have expanded as the ocean froze over and we should see traces of that expansion on its surface. And what we see is a lot of evidence of expansion, but no compression, so that the observations are more consistent with a Pluto hot and starting with a liquid ocean”.
But if Pluto had a source of hot, where did the energy needed to do this? The researchers explain that the two main sources of energy are, on the one hand, the heat released by the decay of radioactive elements in the rocks; and on the other, the gravitational energy released as the new materials were being bombarded the surface of the protoplanet in the distant times of their formation and growth.
The calculations of Bierson show that if all the gravitational energy would have been retained in the form of heat in the interior of the planet, that energy would create, almost inevitably, a liquid ocean initial. However, if the accumulation of new material had been slow, much of that energy would have been radiated away from the surface. “The way in which it formed Pluto -explains Bierson – it is very important for its thermal evolution. If the hot material had accumulated very slowly, I would have spent a lot of energy to the space. But if you had accumulated fast enough, the heat would have been trapped inside.”
The researchers calculated that if Pluto was formed over a period of less than 30,000 years, then its origin was hot. If, instead, the accumulation of material that formed the planet took place over several million years, the origin hot it would have been much more difficult.
The new findings imply that other large objects of the Kuiper belt also could have had a beginning similar. Which means that many of them, like Pluto, could have oceans early, and that in the larger objects, like dwarf planets Eris and Makemake, those oceans could have persisted until our days.
“Even in this cold environment, and so far from the Sun -concludes Bierson – all these worlds could have been born quickly and hot, with oceans of liquid in its interior”.