Standard candle

A standard candle is an astronomical term referring to an object, like certain types of stars or supernovae, whose brightness is known. Because their intrinsic brightness is consistent, astronomers can compare it to how bright they appear from Earth. This comparison helps measure distances in space. If the star looks dimmer, it’s farther away; if it appears brighter, it’s closer. By using standard candles, scientists can accurately determine distances to galaxies and other cosmic objects, improving our understanding of the universe's scale and expansion.