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How Much Does the Earth Weigh? Deborah Hardt, McGrew, Nebraska The Wild File, Outside Magazine, March 2001

Does Anybody Know?

A. Technically, the earth weighs nothing, thanks to that old scientific chestnut that defines weight as a measure of the earth's gravitational pull on another mass.

The real question is: How strongly is the earth and its terrestrial matter attracted to itself -- or, more simply put, what is the earth's own mass? The answer is incomprehensibly huge and impressive enought to toss out with great effect at cocktail parties: 5,972 sextillion metric tons. In pounds, that would be 13,160 followed by 21 zeros.

The figure only came to light a year ago as a bonus factoid while Jens Gundlach, a University of Washington professor of physics, was busy solving a different mathematical conundrum altogether: finding the precise value of the 300-year-old unknown called Newton's Gravitational Constant.

How'd he do it?

The calculations are about as unfathomable as the figure itself, so let's just say he used gold-plated Pyrex dishes, stainless-steel balls, a host of microcomputers, a pen, a notepad, and a cranium full of brains. "The last equation took about ten seconds," boasts Gundlach. "I just did it on a piece of paper."

OK, next time how about the weight of the atmosphere?