By JO-MARIE BROWN
The good news is that Earth may not be vapourised by a solar fireball, as astronomers have widely predicted, when the sun dies in 7.5 billion years' time,
The bad news is that even if the planet orbits its way out of harm's reach, Earth's oceans will
boil themselves dry and the landscape will become a lifeless desert.
Earth's fate has been revised by scientists at Sussex University in England, who now dispute a long-held astrophysical theory that Earth will be consumed when the sun eventually runs out of fuel.
They still predict the sun will balloon into a giant red star, but they say previous calculations suggesting Earth would be swallowed up did not sufficiently account for "solar mass-loss".
The scientists now believe the sun will lose nearly a third of its mass as it expands and a cool wind sweeps it away. In theory this means the sun would exert less gravitational pull on the planets, and Earth would escape by moving into a larger orbit.
However, Mercury would be rapidly consumed and Venus' orbital distance would not expand far enough to spare it.
But the new outlook does not change the fact that humans will need a new home, as the intense heat from the sun would make Earth uninhabitable.
"We had better get used to the idea that we shall need to build our own survival capsules - the planets are simply too far apart for planet-hopping to be a viable solution," the study's authors say.
Canterbury University Professor of Astronomy John Hearnshaw said the results, published in last month's Astronomy and Geophysics journal, were preliminary as the exact amount of mass loss that would occur was poorly understood at present.
"Very likely," he said, "some completely different disaster will have overtaken humanity long before the sun renders our present abode so inhospitable."
