Pluto's Peaks Are Ice Volcanoes, Scientists Conclude

Existence of volcanoes makes idea that dwarf planet is inert ball of ice look increasingly improbable. From a report: Strung out in the icy reaches of our solar system, two peaks that tower over the surface of the dwarf planet Pluto have perplexed planetary scientists for years. Some speculated it could be an ice volcano, spewing out not lava but vast quantities of icy slush -- yet no cauldron-like caldera could be seen. Now a full analysis of images and topographical data suggests it is not one ice volcano but a merger of many -- some up to 7,000 metres tall and about 10-150km across. Their discovery has reignited another debate: what could be keeping Pluto warm enough to support volcanic activity? Sitting at the southern edge of a vast heart-shaped ice sheet, these unusual surface features were initially spotted when Nasa's New Horizons spacecraft flew past in July 2015, providing the first close-up images of the icy former planet and its moons. "We were instantly intrigued by this area because it was so different and striking-looking," said Dr Kelsi Singer, a New Horizons co-investigator and deputy project scientist at Southwest Research Institute in Boulder, Colorado. "There are these giant broad mounds, and then this hummocky-like, undulating texture superimposed on top; and even on top of that there's a smaller bouldery kind of texture." At the time, an ice volcano seemed like the least-weird explanation for these features -- there were no impact craters from asteroids or meteors nearby, suggesting these features had been erased by relatively recent geological events; and no evidence of plate tectonics -- a key contributor to mountain formation on Earth.

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