EARTH will have a narrow escape when the Sun flares up into a supergiant star
near the end of its life.
The ageing Sun will eventually run out of helium fuel in its core, then
expand into a red supergiant star as it burns hydrogen in its atmosphere.
According to the textbooks, this will make the Earth too hot for life in 5.5
billion years鈥� time, and the Sun could be large enough to engulf our planet in
7.5 billion years.
But new calculations by Robert Smith and colleagues at the University of
Sussex say Earth will survive. They say that as the Sun burns up fuel it will
lose mass and its gravitational hold on the Earth will weaken. Taking this into
account, they have shown life could persist for 5.7 billion years and that the
Sun won鈥檛 swallow the Earth after all (Astronomy & Geophysics, vol
42, p 6.26).
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