Earth's Final Sunset Predicted > By Clara Moskowitz
> Staff Writer
> posted: 2008 February 26
> 07:00 am ET
>
> "Some say the world will end in fire, Some say in
> ice," wrote the poet Robert Frost. Astronomers, it
> turns out, are in the former camp.
>
> A new calculation predicts that Earth will be
> swallowed up by the sun in 7.6 billion years,
> capping off a longstanding debate over whether the
> sun's gravitational pull will have weakened enough
> for Earth to escape final destruction or not.
>
> Other theorists have predicted that our planet will
> fry as the sun expands in its old age. But the time
> estimates have varied by a couple billion years.
>
> "Although people have looked at these problems
> before, we would claim this is the best attempt
> that's been made to date, and probably the most
> reliable," said astronomer Robert Smith, emeritus
> reader at the U.K.'s
University of Sussex, who made
> the new calculations with astronomer Klaus-Peter
> Schroeder of the University of
Guanajuato in
Mexico.
> "What we've done is to refine existing models and to
> put the best calculations we can at each point in
> the model."
>
> If 7.6 billion years doesn't sound like an urgent
> death sentence, don't relax yet. Regardless of
> whether Earth will ultimately be vaporized, as the
> sun heats up, our planet will become too hot to live
> on before then.
>
> "After a billion years or so you've got an Earth
> with no atmosphere, no water and a surface
> temperature of hundreds of degrees, way above the
> boiling point of water," Smith told
SPACE.com. "The
> Earth will become dry basically. It will become
> completely impossible for life of any kind to exist.
> It's a pretty gloomy forecast."
>
> Nonetheless, scientists are curious about the
> ultimate fate of our planet after we are gone (like
> all previous hominids and more than 99 percent of
> all species that have lived on Earth, humans will
> probably go extinct, and it will likely happen
> sooner than a billion years).
>
> Smith's earlier studies found that Earth would
> narrowly escape being engorged. As the sun ages and
> expands into a red giant star, it will shed its
> outer gaseous layers, thus losing mass and weakening
> its gravitational pull. Previous calculations found
> that this let-up would allow the Earth's orbit to
> shift outward, enabling the planet to slip free of
> the smoldering sun.
>
> But this scenario doesn't account for tidal forces,
> and the drag of the sun's outer layers. As the Earth
> orbits the sun, its smaller gravitational pull isn't
> completely negligible - it actually causes the side
> of the sun closest to our planet to hoard more mass
> and bulge out toward us.
>
> "Just as the Earth is pulling on the sun's bulge,
> it's pulling on the Earth, and that causes the Earth
> to slow in its orbit," Smith said. "It will spiral
> back and finally end up inside the sun."
>
> In addition, the gas that the sun expels will also
> drag Earth inward toward its demise.
>
> Smith's previous calculations had ignored these
> effects.
>
> "We didn't think it mattered, but it turns out it
> does," he said. "You might say our previous models
> had a gap."
>
> There may even be hope for Earth. Some scientists
> have proposed a scheme for down the road to use the
> gravity of a passing asteroid to budge Earth out of
> the way of the sun toward cooler territory, assuming
> there is life around at the time that is intelligent
> enough to engineer this solution.
>
> "It sounds like science fiction, but there's a group
> of people who have quite seriously suggested that it
> might be possible," Smith said. "If it's done right,
> that would just keep the Earth moving fast enough to
> keep it out of harm's way. Maybe life could go on
> for as much as 7 billion years."
>
> Smith's findings have been accepted for publication
> in the journal Monthly Notices of the Royal
> Astronomical Society.
Is it the right time to think about moving to Mars?
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NEW YORK, Feb. 14, 2008 – Ten years after Wyoming college student Matthew Shepard was brutally murdered because of his sexual orientation, a 15-year-old gay California student is dead after a student allegedly shot him because of his sexual orientation and gender expression.
tired
calm
