how scientist got to know the weight of our planets?

Question

i want to know the formula or method. how do they come to able weighing on a physical balance a planet!

plzzz clear up my mind

Answer 1

The first approximate determination of the weight of the Earth was in 1774 by the British Astronomer Royal, Nevil Maskelyne.

He used star observations to find the difference between the gravitational vertical and the astronomical vertical around the Scottish mountain Schiehallion, which is rather isolated and has a fairly regular shape. In effect, he measured how far sideways it would pull a plumbline which would otherwise have pointed straight downwards. By estimating the volume and density of the mountain, and using Newton's inverse square law, he then got the mass of the Earth within 20 per cent. Its average density turned out to be about 5 times that of water, while surface rocks are around 2.9 to 3.0, so this showed that the earth was not just a big ball of rock.

The modern method is to use a "torsion balance" with long long arms and big weights at its ends. This can measure the actual attractive force of another stationary big weight, hence the G in Newton's formula F = G.m1.m2 / d^2 which as a previous answerer says is enough to then deduce the mass of the earth.

Answer 2

Of course, you mean mass.

No need for any guessing about what Earth is composed. The mass of Earth can be calculated by Newton's Law of Gravity:

F = GmM/r2 = ma, where F is the gravitational force, G is the gravitational constant, M is the mass of the Earth, r is the radius of the Earth, and m is the mass of another object (near the surface of the Earth).

From this, we can calculate the mass of Earth to be 6E24 kg.

Now just do the same for sun and planets. Details in the Scientific American article below.

Answer 3

Mass, not weight. Weight has to do witht he attraction between the mass (earth) and its effects on other objects (us, the moon, etc). You can't weight the earth because the earth isn't on the earth.

To get the mass they first have to assume the know what the center of the earth is made of. They guess at the percentages of whats what. They know that the mass of 1cc of core and magma has "x" mass and there is "y" amount of space in the sphere that is earth there fore the earth must have "z" mass. Hope I made sense, cuz I'm heavily medicated right now and I can't sleep.

Answer 4

weight can not be calculated only mass is. Weight would have to be relative to something or the earth has to be on an another bigger planet like Jupiter (not possible btw) and still it would vary from planet to planet. For example your weight is calculated by multiplying your mass with gravity. So your weight is measured relative to earth. And your weight on the moon would be less because gravity of moon is less so your weight would vary depending on location.

Answer 5

Didn't Atlas have it on his shoulders ..at one time ..i seen the photos ..lol