Thursday, September 26, 2013
Life on Earth has only 1.75 billion years left
The Earth's days are numbered, and the planet could become too hot to inhabit in as soon as 1.75 billion years, according to one researcher.
Scientists have done the math, and according to their calculations, life on Earth has 1.75 billion to 3.25 billion years left to thrive.
And that's if a giant asteroid or a nuclear war doesn't finish us off first.
Yes, there is a big difference between 1.75 billion and 3.25 billion years, but predicting the end of life on our planet it is not an exact science, at least not yet.
To arrive at that 1.5-billion-year doomsday spread, graduate student Andrew Rushby of the University of East Anglia in Britain created two slightly different equations that estimate the length of time Earth will remain in the "habitable zone" around the sun.
A planet is considered to be in the habitable zone when liquid water can exist on its surface.
If Earth was too close to the sun, high temperatures would cause our oceans to evaporate; too far away, and we'd be an icy wasteland.
Earth is firmly in the habitable zone of our sun right now (obviously — we're all here!), but that won't always be the case, Rushby explains in a new paper published in the journal Astrobiology.
As our sun gets older, it will evolve into a bigger, more luminous star. And sometime between 1.75 billion years and 3.25 billion years from now, Rushby says, the 92.9 million miles between us and our host star will not be enough to keep us comfortable.
Instead of being in the habitable zone, Earth will be in what astronomers call the hot zone. Oceans, liquid water and life will cease to exist on the planet.
Though it may be interesting to consider the final days of life on planet Earth, Rushby's equations were really designed to help astronomers determine whether newly discovered planets are in the habitable zones around their host stars, and how long they will stay there.
In any event, there's no reason to fixate on the 1.75-billion-year deadline. Earth will become inhospitable to humans long before the planet enters the hot zone, Rushby told Norwich Evening News 24.
"Humans would be in trouble with even a small increase in temperature, and near the end only microbes in niche environments would be able to endure the heat," he said.
Article Source here
Author:
Deborah Netburn of McClatchy-Tribune News Service
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