Stars · The Sun · Physics
Luminosity
Say it: loo-mih-NOSS-ih-tee IPA: /ˌluməˈnɑsəti/ noun
Luminosity: The total power a star or other object gives off as light and other radiation, in all directions.
How bright a star looks depends on its distance as well as its output. Luminosity leaves distance out: it is the star's whole output, wherever we happen to be.
- Example
- A star that looks faint can still have a far greater luminosity than the Sun if it is very far away.
- Why astronomers use it
- Together with temperature, it tells astronomers how large a star is and how far along in its life it has come.
- Tiny cosmic connection
- The Sun's luminosity, about 3.8 × 10²⁶ watts, is the yardstick for other stars, whose luminosity is often given in Suns.
Observatory Stars The Sun Physics
Where to check it
Written for Cool Moon Facts in its own words; the sources cover the same idea in more depth.