A THIRD of a tonne of extraterrestrial bacteria could be raining down on
Earth every day. The controversial claim comes from scientists who say they have
found microbes living more than 40 kilometres above the Earth’s surface.
Ever since the 1970s astronomers Fred Hoyle and Chandra Wickramasinghe have
backed the idea that Earth was seeded with life from space. They think microbes
hitchhike around the Universe on comets. Although the bacteria would spend much
of the time frozen, radiation from the Sun would warm a comet’s surface when it
got close enough, making it shed microbes that might just fall…
