# luminosity

/lˌuːmɪnˈɒsɪti/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/luminosity
Updated: 2026-05-19

## Definition

the amount of light that an object gives off. In astronomy, it helps scientists measure how bright a star is compared to our sun.

For teachers: the total amount of electromagnetic radiation emitted by an astronomical object per unit of time. Often used to describe the intrinsic brightness of a star or galaxy.

## Examples

- The star has a high luminosity.
- Astronomers use luminosity to determine the distance to a galaxy by comparing its apparent brightness to its actual output.
- While the star appears dim to the naked eye, its immense luminosity suggests it is a massive, young object located far beyond our solar system.

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