Thread: Weighing the planet earth.

Kind of a foolish little question, but who was the first person to weigh the earth and how did they get their result?

The Earth is in free fall so it has no weight. So, "Who was the first person to determine the mass of the Earth?"

I always thought that it was Newton but maybe it wasn't till 1798: the British scientist Henry Cavendish.

Cavendish experiment - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Cavendish_experiment#Derivation_of_G_and_the_Earth .27s_mass

After converting to SI units, Cavendish's value for the Earth's density, 5.448 g cm⁻³, gives

G = 6.74 × 10⁻¹¹ m³ kg⁻¹ s⁻², which differs by only 1% from the currently accepted value: 6.67428 × 10⁻¹¹ m³ kg⁻¹ s⁻².