Last exit to Andromeda

摘要

A hundred and sixty million years ago, a star was coursing casually through space when it came across a black hole. It could have been a disaster for the star, but it was lucky: it wasn't quite close enough to be swallowed. Instead it was flung away across space at an unimaginable speed. In December 2004, Warren Brown, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, saw this very star. It was travelling away from Earth at 850 kilometres a second - fast enough for it to escape the galaxy altogether. When Brown told his colleagues what he had in his telescope's sights, they thought he'd lost his mind. "You have a what?!" yelled Margaret Geller of the Smithsonian Astrophysical Observatory, also in Cambridge.