<p>Newton's analysis of Kepler's laws lets you determine the ratios of the masses of everything in the solar system with quite high precision, but it doesn't let you determine the actual mass.  The actual masses were one of the large unsolved problems of physics for almost a century, until 1798 when <a href="https://en.wikipedia.org/wiki/Cavendish_experiment" rel="noreferrer">Cavendish's work with a torsion balance</a> (described by him as "weighing the world") determined the density of Earth, from which the masses of everything could be computed.</p>

CC BY-SA 3.0
2014-05-19T03:04:18.127Z
2014-05-19T03:04:18.127Z
Mark
<p>I was scrolling through the list of <a href="http://en.wikipedia.org/wiki/Moons_of_Jupiter">moons of Jupiter</a> and I wondered how astronomers where able to determine the masses of those objects. When I tried to google it I meanly found results of people deriving the mass of Jupiter from the masses of its moons using Kepler's laws. So the mass of celestial bodies with satellite(s) can be estimated this way. But what about the rest? Or are they all derived from the trajectories of man-made satellites passing near them?</p>

<mass>
How are the masses of celestial bodies determined?
fibonatic
# How are the masses of celestial bodies determined?

(Asked by: username_0 on 2014-05-18)

I was scrolling through the list of [moons of Jupiter](http://en.wikipedia.org/wiki/Moons_of_Jupiter) and I wondered how astronomers where able to determine the masses of those objects. When I tried to google it I meanly found results of people deriving the mass of Jupiter from the masses of its moons using Kepler's laws. So the mass of celestial bodies with satellite(s) can be estimated this way. But what about the rest? Or are they all derived from the trajectories of man-made satellites passing near them?

**Tags:** mass


---

## 1 answers

### Answer by username_1 on 2014-05-19. Score: 5

Newton's analysis of Kepler's laws lets you determine the ratios of the masses of everything in the solar system with quite high precision, but it doesn't let you determine the actual mass. The actual masses were one of the large unsolved problems of physics for almost a century, until 1798 when [Cavendish's work with a torsion balance](https://en.wikipedia.org/wiki/Cavendish_experiment) (described by him as "weighing the world") determined the density of Earth, from which the masses of everything could be computed.


---

