The solar system's coldest surface shouldn't be erupting, yet Triton's nitrogen geysers forced scientists to rethink what "dead" really means in the deep freeze. The post Voyager 2 passed Neptune’s moon Triton in 1989 and photographed it erupting, a discovery scientists called the flyby’s biggest surprise — dark plumes rising nearly eight kilometres and then drifting 150 kilometres downwind, on the coldest surface known appeared first on Space Daily .