Monday, January 30, 2012

Who, What, Why: Is the Earth getting lighter? By Charlotte McDonald (BBC NEWS MAGAZINE)


The recent crash landing of Russian spacecraft Phobos-Grunt has focused attention on the increasing amount of space junk orbiting the planet. So does this mean the Earth has been getting lighter? The BBC's Radio 4 programme More or Less turned to a group of Cambridge University academics for the answer.
There are factors that are causing Earth to both gain and lose mass over time, according to Dr Chris Smith, a medical microbiologist and broadcaster who tries to improve the public understanding of science.
Using some back-of-the-envelope-style calculations, Dr Smith, with help from physicist and Cambridge University colleague Dave Ansell, drew up a balance sheet of what's coming in, and what's going out. All figures are estimated.
By far the biggest contributor to the world's mass is the 40,000 tonnes of dust that is falling from space to Earth, says Dr Smith.
"[The dust] is basically the vestiges of the solar system that spawned us, either asteroids that broke up or things that never formed into a planet, and it's drifting around.
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