Astronomy
How Binary Star Systems Help Determine Stellar Masses
Quick fact
The only direct way to measure a star's mass is through its gravitational interaction with another star in a binary system, using the precise laws of orbital motion discovered by Kepler and Newton.
Why this is interesting
Have you ever wondered how astronomers know the mass of a star, even though they can't put it on a scale? The answer lies in binary star systems—two stars orbiting each other like celestial dancers.