THE Hubble Space Telescope may soon be able to see other Earths – or at least those on their last legs – by detecting their evaporating oceans.
Almost all the extrasolar planets we know about are Jupiter-sized gas giants, Earth-sized ones being too small for existing methods to detect. But Michael Jura of the University of California in Los Angeles points out that any planet like Earth will eventually warm up as its star gets older and brighter. The oceans will start to evaporate, sending water vapour into the upper atmosphere, where ultraviolet light will split it into hydrogen and oxygen. Jura…
