how do scientists calculate the mass of planet's?

Answer 1

First, get its radius. Compute volume for the planet.

Next, determine the planet's composition. This is done by looking at how fast the planet rotates and comparing it to the size of the planet. The composition is then translated into mass by seeing how heavy a particular material in the planet is, and checking it against the percentage of said material in the planet. Furthermore, mass is computed and verifeid by looking at the gravitational effects created by the planet.

Finally, density=mass/volume, Take note, this is the average density.

Answer 2

If the planet has a moon, you can easily calculate the mass of the planet from the orbit of the satellite. For a circular orbit, the following is true:

GmM/r^2 = mv^2/r

G is the gravitational constant
m is the mass of the satellite
M is the mass of the planet
v is the speed of the satellite
r is the radius of the orbit

Canceling, you get:

M= rv^2/G

You don't need the mass of the satellite, just some good astronomical observations of the radius and speed.

Answer 3

By observing them and their interactions with other planets, with the sun and with their moons.

There are precise equations involving the orbits and masses of heavenly bodies, based on laws of gravitation and motion worked out originally by Newton and Kepler. So, scientists observe the orbits and distances and essentially treat the masses as unknowns (like x's in an algebra problem) to be solved for. It gets into some pretty hairy math, of course, but the general concept is relatively simple.

It even works these days for planets orbiting distant stars. Astronomers observe slight variations -- wobbles, as it were -- in the trajectory of a star, and through some even hairier math, can work out the size and distance of a planet that is causing the wobbles. That's because not only does a star (like our sun) exert gravitation pull on its planets (like the earth), but the planets exert gravitational force on the stars, though a lot less. And, the bigger the planet, the more force it exerts on its star, and the more the star "wobbles."

Answer 4

How do scientists measure or calculate the weight of a planet?

Rusi Yan
Marlborough, Mass.

Barry Lienert, a geophysicist at the University of Hawaii, provides the following explanation.
We start by determining the mass of the Earth. Issac Newton's Law of Universal Gravitation tells us that the force of attraction between two objects is proportional the product of their masses divided by the square of the distance between their centers of mass. To obtain a reasonable approximation, we assume their geographical centers are their centers of mass....
this is very lengthy, click here to read the rest
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Answer 5

Yes it is a problem you have two unknowns here the mass and distance. What is needed is an independent way to find sun/planet distances. This involves some complex stuff with paralax and transits, but I'm not entirely sure of the procedure.

Answer 6

mass is related to volume and density. so if 2 of these are known, then you can solve for the 3rd. density = mass/volume

Answer 7

They build a smaller version in a laboratory, weight it, then extrapolate to the big version.

Answer 8

That very question was posed and answered on this web page: