An Etymological Dictionary of Astronomy and Astrophysics

The puzzle of why the night sky is not as uniformly bright as the surface of the Sun if, as used to be assumed, the Universe is infinitely large and filled uniformly with stars. It can be traced as far back as Johannes Kepler (1571-1630), was discussed by Edmond Halley (1656-1742) and Philippe Loys de Chéseaux (1718-1751), but was not popularized as a paradox until Heinrich Olbers took up the issue in the nineteenth century. This paradox has been resolved by the → Big Bang theory. In a Universe with a beginning, we can receive light only from that part of the Universe close enough so that light has had time to travel from there to here since the Big Bang. The night sky is dark because the galaxies are only about ten billion years old and have emitted only a limited amount of light, not because that light has been weakened by the expansion of the Universe (P. S. Wesson et al., 1987, ApJ 317, 601).

See also: Formulated in 1826 by Heinrich Wilhelm Olbers (1758-1840),
German physician and amateur astronomer, who discovered the asteroids Pallas and Vesta as well as five comets; → paradox.