# The Naked Scientists Forum

### Author Topic: How did scientists calculate the mass of the Earth and Sun  (Read 1283 times)

#### syhprum

• Neilep Level Member
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##### How did scientists calculate the mass of the Earth and Sun
« on: 08/06/2010 20:46:03 »
I could not resist this follow up from the previous question "How did scientists calculate the radius of the Earth and Sun"

#### Soul Surfer

• Neilep Level Member
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• keep banging the rocks together
##### How did scientists calculate the mass of the Earth and Sun
« Reply #1 on: 09/06/2010 08:44:16 »
A set of experiments was done on earth to measure the gravitational attractions between balls of various masses.  This defined the gravitational constant which was found to be the same fro an equal mass of any material.

The distances and orbital periods of the earth moon and sun have been known from earlier measurements and therefore using Newtons law of gravitation and the gravitational constant it is possible to calculate the masses of the earth moon and sun.
« Last Edit: 09/06/2010 08:46:08 by Soul Surfer »

#### graham.d

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• Posts: 2208
##### How did scientists calculate the mass of the Earth and Sun
« Reply #2 on: 09/06/2010 10:23:50 »
If I have done the maths right:

Mass of the sun = ω²*r³/G

Where r is distance from sun to planet and ω is angular speed (= 2πf)

#### The Naked Scientists Forum

##### How did scientists calculate the mass of the Earth and Sun
« Reply #2 on: 09/06/2010 10:23:50 »