Flaw In Theory Of Earth's Fiery Demise
[Original headline: Our future a little brighter as sun dies ]
The end may not be as nigh as we thought after a team of scientists discovered that the Earth could escape being destroyed by a solar fireball when the sun runs out of fuel.
For decades, astronomy textbooks have said the Earth will be engulfed in an inferno billions of years from now as the dying sun swells into a gigantic red star.
But a team of astrophysicists at Sussex University in England has uncovered a flaw in this theory.
Previous scientific calculations suggested that the sun would balloon out and engulf the Earth about 7.5 billion years from now. But the team says these calculations missed out a crucial effect: the loss of mass of the dying sun as it expands and its gravity weakens.
They predict that the Earth will manage to dodge a fiery fate, its orbit expanding away from the swelling sun.
Robert Smith, one of the team, says the sun will make two attempts to destroy the Earth. In the first, about 7.7 billion years from now, it will expand to about 120 times its current size, engulfing Mercury and Venus.
Its weakened gravity will allow the Earth to escape a similar fate, however, with our planet settling down into an orbit that is 25 per cent bigger - well clear of the sun's outer atmosphere.
About 100 million years later the dying sun will have another go at the Earth, but will fail again, with our planet having moved out even farther away.
Dr Smith, who reports the findings in the current issue of the journal Astronomy and Geophysics, says the sun will then collapse into a harmless white dwarf star, 16,000 kilometres wide.
"They [the findings] differ from the standard conclusion by taking account of mass loss and including the latest data based on studies of real stars. To that extent, the textbooks will have to be rewritten."
Story originally published by:
The Sunday Telegraph, London via Sydney Morning Herald / Australia | Robert Matthews - Jan 07.02
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