 One of the twin Voyager spacecraft. Voyager 1 and Voyager 2 were launched in 1977 from Cape Canaveral, Fla. (NASA/AFP) | | | We live inside a bubble scientists call the "heliosphere." It's a region of space carved out by the solar wind, a stream of gas and particles flowing off the sun. Inside it, our solar system, our world, our fragile selves are protected from the myriad hazards of interstellar space: deep cold, powerful radiation, other unknown threats. But this time last year, for only the second time in history, a human-made object burst through that bubble, abandoning the protection of the heliosphere for whatever lies beyond. What the NASA spacecraft Voyager 2 has discovered at the edge of the solar system confirms the clues picked up by its twin when it ventured into this region in 2012. According to a suite of papers published this week in the journal Nature Astronomy, interstellar space is a vast ocean of cold, dense plasma — a gas composed of atoms that have lost some of their electrons. Occasionally, particles from the solar wind trickle into it, like a stream pouring into the sea. The thing about leaving home is it gives us an opportunity to turn around and look back at the place we came from, seeing it through new eyes. When the Apollo 8 astronaut Bill Anders photographed Earth rising behind the moon for the first time, he was struck by the thought that "this is not a very big place," he said at a 50t- anniversary celebration last year. It was strange, he thought, that he had traveled so far, risked so much, to study the moon. "And what we really discovered was the Earth." Now, from the shores of the universe, one of humanity's explorers has delivered an image of ourselves as we truly are: puny. Privileged. Passengers on a life raft inflated by the breath of the sun, drifting on the vast galactic sea. |
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