"Triton is of importance as it offers clues to what geologic features might look like on Pluto, given that the icy crusts of both bodies are probably rather similar and would presumably react in similar ways under internal stress and heat," he added. "So if there were or are volcanoes on Pluto, they could look similar to those we see on Triton."
Voyager 2 launched in August 1977, a few weeks before its twin, Voyager 1. The pair conducted an unprecendented "grand tour" of the outer solar system, returning good looks at the Jupiter, Saturn, Uranus and Neptune systems.
Both Voyager 1 and Voyager 2 then kept right on flying. Voyager 1 entered interstellar space in August 2012, and Voyager 2 (which took a different route through the solar system) is poised to do so soon.
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