SCIENTIFIC BLOGGING – University of Sussex astronomers predict that the Earth will be swallowed up by the Sun unless the Earth’s orbit can be altered – but we have about 7.6 billion years to do it. Dr Robert Smith, Emeritus Reader in Astronomy, said his team previously calculated that the Earth would escape ultimate destruction, although be battered and burnt to a cinder, but they did not take into account the effect of the drag caused by the outer atmosphere of the dying Sun. . . Life on Earth will have disappeared long before 7.6 billion years, however. Scientists have shown that the Sun’s slow expansion will cause the temperature at the surface of the Earth to rise. Oceans will evaporate, and the atmosphere will become laden with water vapor, which (like carbon dioxide) is a very effective greenhouse gas. Eventually, the oceans will boil dry and the water vapor will escape into space. In a billion years from now the Earth will be a very hot, dry and uninhabitable ball. Can anything be done to prevent this fate? Professor Smith points to a remarkable scheme proposed by a team at Santa Cruz University, who suggest harnessing the gravitational effects of a close passage by a large asteroid to “nudge” the Earth’s orbit gradually outwards away from the encroaching Sun. A suitable passage every 6000 years or so would be enough to keep the Earth out of trouble and allow life to survive for at least 5 billion years, and possibly even to survive the Sun’s red giant phase. http://www.scientificblogging.com/news_releases/dont_worry_the_sun_will_only_vaporize_earth_if_we_dont_change_our_orbit