Earth Might Survive Sun’s Explosion
By DENNIS OVERBYE
What happens to planets when their stars age and die?
That’s not an academic question. About five billion years from now, astronomers say, the Sun will run out of hydrogen fuel and swell temporarily more than 100 times in diameter into a so-called red giant, swallowing Mercury and Venus and dooming life on Earth, but perhaps not Earth itself.
Astronomers are announcing that they have discovered a planet that seems to have survived the puffing up of its home star, suggesting there is some hope that Earth could survive the aging and swelling of the Sun.
The newly discovered planet is a gas giant at least three times as massive as Jupiter. It orbits about 150 million miles from a faint star in the constellation Pegasus known as V 391 Pegasi. But before that star blew up as a red giant sometime in the past and lost half its mass, the planet must have been about as far from its star as the Earth is to the Sun — about 90 million miles — the astronomers led by Roberto Silvotti of the Observatorio Astronomico di Capodimonte in Naples, Italy, calculated.
Dr. Silvotti said that the results showed that a planet at the Earth’s distance “can survive” the red giant and he hoped the discovery would spur searches for more like it. “With some statistics and new detailed models we will be able to say something more even to the destiny of our Earth (which, as we all know, has much more urgent problems by the way),” he said in an e-mail message.
He and his colleagues report their results in Nature on Thursday.
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