Caption: Determining the Earth's mass.

The accepted value for the Earth's mass is Earth mass M_⊕ = 5.9722(6)*10**24 kg = 3.0033*10**(-6) M_☉.

Note we have used the astronomical symbols the Earth symbol ⊕ and the Sun symbol ☉ to label the masses for the Earth and Sun.

For the calculation to be independent of astronomical object masses, the gravitational constant G = 6.67430(15)*10**(-11) (MKS units) must be determined in the laboratory. This has been done though NOT to as a high an accuracy/precision as other fundamental physical constants (see NIST: Fundamental Physical Constants). In fact, the first reasonably accurate measurement was the Cavendish experiment (1798, G_obtained = 6.74*10**(-11) MKS units) which is pretty good for 1798.

Credit/Permission: © David Jeffery, 2003 / Own work.
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