London, Feb 23 : A new study has suggested that the Earth would face destruction when the Sun expands into a red giant in about 7.6 billion years from now.
According to a report in New Scientist, when our sun's red giant phase would begin, the Earth will be dragged into its atmosphere to a fiery demise.
In a few billion years, the Sun will fuse the last of its hydrogen into helium, turn into a red giant and expand to 250 times its current size.
At first, the Sun's loss of mass will loosen its gravitational pull on Earth, which will allow the planet to migrate to a wider orbit about 7.6 billion years from now.
"This process has led some to speculate that the Earth might escape destruction - but survival now seems impossible," said Peter Schr"der of the University of Guanajuato in Mexico and Robert Smith of the University of Sussex in the UK.
These researchers created the most detailed model to date of the Sun's transition to a red giant, based on observations of six nearby red giant stars.
What they found was that Earth's orbit will widen at first. But Earth will also induce a "tidal bulge" on the Sun's surface, with its own gravitational pull.
The bulge will lag just behind the Earth in its orbit, slowing it down enough to drag it to a fiery demise.
Another factor is that the tenuous outer atmosphere of the sun extends a long way beyond its visible surface, and the Earth would be orbiting within these very low density outer layers.
The drag caused by the low-density gas would be enough to cause the planet to drift inward to be consumed by the sun.
However, if Earth remains in its current orbit, life isn't likely to be here in 7.6 billion years.
As the sun expands in its end sequence, Earth's surface temperatures will rapidly rise causing oceans to evaporate, leaving a hot, dry and uninhabitable ball.