How much does the Earth weigh?
8 September 2014 Last updated at 11:41 BST
How much does the earth weigh?
According to Terry Quinn, emeritus director of the International Bureau of Weights and Measures, the Earth weighs about 7,000,000,000,000,000,000,000,000 Kg.
Beyond this, he explained to Today programme presenter John Humphrys, scientists are now examining the accuracy of measurements of G, the Newtonian constant of gravitation, as "the results we are getting are widely diverse".
G, which sets the scale of gravity, was first measured at the end of the 18th century to an accuracy of around one per cent.
But, he explained, recent findings from scientists from around the world, have differed widely, indicating "we're not doing our measurements correctly".
A special issue of the Philosophical Transactions of The Royal Society A* is published today exploring the issue.
First broadcast on BBC Radio 4's Today programme on Monday 8 September.