In 2015, NASA's New Horizons space probe flew by Pluto and found the presence of ammonia on the surface of the dwarf planet.

Now, a new study suggests that the whiff of ammonia in the reddish ice of the distant world was left over from a recent geological activity — one where a volcano spewed liquid water instead of molten lava.

The findings, which were published in the journal Science Advances, hints at the existence of an ocean full of liquid water beneath the surface of Pluto.

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