How do we accurately estimate the mass of the earth/planets?

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Dory
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How do we accurately estimate the mass of the earth/planets?

Post by Dory » Sun Sep 26, 2010 6:09 am

What do scientists come up with to educatedly guess the mass of the earth?

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Re: How do we accurately estimate the mass of the earth/plan

Post by GenesForLife » Sun Sep 26, 2010 6:32 am

F = Gm1m2/r2 = ma ----- (1)

Gm/r2 = g ------- (2)

m = gr2/G

m = (9.8 m/s2)(6.37 × 106 m)2/(6.673 × 10-11 Nm2/kg2)

m = 5.96 × 1024 kg

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Re: How do we accurately estimate the mass of the earth/plan

Post by GenesForLife » Sun Sep 26, 2010 6:35 am

The other approach would be to calculate the radius of the earth and factor that in to obtain the mass.

M = g r2/ G

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Re: How do we accurately estimate the mass of the earth/plan

Post by Xamonas Chegwé » Sun Sep 26, 2010 6:36 am

Ask Wiki!

http://en.wikipedia.org/wiki/Planetary_mass
The mass of a planet within the Solar System is an adjusted parameter in the preparation of ephemerides. There are two basic procedures for measurement:
  • If the planet has natural satellites, its mass can be calculated from Kepler's third law. The same procedure can be used for data from space probes such as the Voyager probes to the outer planets and the MESSENGER spacecraft to Mercury.
  • The mass of a planet can also be inferred from its effect on the orbits of other planets.
In practice, both methods are used. The ephemeris is a model of the Solar System, and the planetary masses within that model are adjusted so as to give the best fit between the model and the observed positions of the planets.
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Re: How do we accurately estimate the mass of the earth/plan

Post by Dory » Sun Sep 26, 2010 7:04 am

Oh, so you just measure gravitional pulls? Neat!
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Re: How do we accurately estimate the mass of the earth/plan

Post by Deep Sea Isopod » Sun Sep 26, 2010 8:06 am

I was trying to imagine someone walking around the world with one of those meter counting wheel thingies. :?
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Re: How do we accurately estimate the mass of the earth/plan

Post by Gawdzilla Sama » Sun Sep 26, 2010 12:01 pm

The mother of all bathroom scales. (The planets disrobe before being weighed so they get an "accurate" weight. Then they find a way to justify that extra slice of cheesecake while watching the telly.
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Re: How do we accurately estimate the mass of the earth/plan

Post by Tero » Sun Sep 26, 2010 12:40 pm


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Re: How do we accurately estimate the mass of the earth/plan

Post by Feck » Sun Sep 26, 2010 12:46 pm

Gawdzilla wrote:The mother of all bathroom scales. (The planets disrobe before being weighed so they get an "accurate" weight. Then they find a way to justify that extra slice of cheesecake while watching the telly.
Use a cosmic scale .

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Re: How do we accurately estimate the mass of the earth/plan

Post by Gawdzilla Sama » Sun Sep 26, 2010 12:50 pm

Feck wrote:
Gawdzilla wrote:The mother of all bathroom scales. (The planets disrobe before being weighed so they get an "accurate" weight. Then they find a way to justify that extra slice of cheesecake while watching the telly.
Use a cosmic scale .
Dude! That is so . . . cosmic, man!

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Re: How do we accurately estimate the mass of the earth/plan

Post by mistermack » Mon Sep 27, 2010 3:30 pm

No matter how hard I push the earth down away from me with my feet, gravity pulls it back up with an acceleration of 1g.
So I shoud be able to work out the mass of the earth, If I know the distance to it's centre of gravity, and my own mass.
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