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Weighing planets and stars


(September 2000)


According to a report posted on the Internet during September, a University of Washington group has reduced the uncertainty in the value of G, the universal gravitational constant, by almost a factor of ten. Their preliminary value is G = 6.67390 x 10-11 m3/kg/s2, with an uncertainty of 0.0014%.


Combining this new value of G with measurements made with the Lageos satellite (which uses laser ranging to keep track of its orbital position to within a millimeter) permits the calculation of a brand new, highest precision mass for the earth of


5.97223 (+/- 0.00008) x 1024 kg


Similarly, the new mass of the sun becomes 1.98843 (+/- 0.00003) x 1030 kg.


For more detail, see and