There’s probably only one question going through you’re head right about now. ‘Which bathroom scales did you use to measure that then?’

The Earth’s mass, estimated at 6,000,000,000,000,000,000,000,000 kilograms is actually derived by using information about it’s gravitational attraction to surrounding objects. 2 objects that have a mass, will have a gravitational attraction for each other.

There is a formula that tells us the gravitational force between 2 speherical objects. We know the Earth isn’t perfectly spherical but let’s not be picky!. It is:

F = G(M1*M2/R^{2})

**F**being the force of attraction between them.**G**is a constant that is 6.67259 x 10^{-11}m^{3}/kg s^{2}.**M1**and**M2**are the two masses that are attracting each other.**R**is the distance separating the two objects.

M1 is the mass of the Earth and M2 is any other mass, e.g a medicine ball.

F is calculated by dropping a mass, in this example the medicine ball, and measuring the acceleration that the Earth’s gravitational force applies to it. A 1kg medicine ball would give a force between them of 9.8 kg*m/s^{2}.

Finally by using the information that the Earth has a radius of 6,400,000 metres, we can plug in the values, do some rearranging of the formula and come to a conclusion that the mass of the Earth is 6,000,000,000,000,000,000,000,000. Simple right?

If that isn’t complicated enough, it is estimated that the mass of the Earth increases by around 45,000kg per year because of increasing dust.

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