Measurement of Newton's constant using a torsion balance with angular acceleration feedback

We measured Newton's gravitational constant G using a new torsion balance m ethod. Our technique greatly reduces several sources of uncertainty compare d to previous measurements: (1) It is insensitive to anelastic torsion fibe r properties; (2) a flat plate pendulum minimizes the sensitivity due to th e pendulum density distribution; (3) continuous attractor rotation reduces background noise. We obtain G = (6.674215 +/- 0.000092) X 10(-11) m(3) kg(- 1) s(-2); the Earth's mass is, therefore, M+ = (5.972245 +/- 0.000082) X 10 (24) kg and the Sun's mass is M-. = (1.988435 +/- 0.000027) X 10(30) kg.