Assertion: asteroid belt's mass | /r/HasProperty | calculated
Facets:
value: from their orbits
type: OTHER
value: from perturbations
type: OTHER
value: except for asteroids
type: OTHER
Source sentences:
text: The masses of asteroids are calculated from perturbations they induce on the orbits of other asteroids, except for asteroids that have been visited by spacecraft or have an observable moon, where a direct mass determination is possible.
text: Because Haumea has moons, the mass of the system can be calculated from their orbits using Kepler's third law.