A lot? Bit? Want to know how much the Earth weighs?

  • Science
  • BBC World, @bbc_ciencia

image sources, Thinkstock

To find out how much the Earth weighs, you have to take gravity into account and read this note to the end.

And how is gravity measured? The strength of the force that keeps the Moon orbiting the planet and us down to earth is determined by what physics calls “G”, the universal gravitational constant.

image sources, Wikimedia Commons


Henry Cavendish was the first to calculate the density and weight of the Earth.

“Newton’s law of gravity describes the motion of planets and moons with amazing precision, and what we call Newton’s gravitational constant is what determines the scale, the magnitude of gravity,” explained to BBC Terry Quinn, Director Emeritus of the International Bureau of Weights and Measures.

“Small-scale gravity is very small, large-scale gravity is very, very large,” the expert said. Therefore, calculating a constant value was a challenge.