emission nebula

Noun

emission nebula (plural emission nebulae or emission nebulas)

1. A nebula composed of ionized gases which produce visible light (as distinct from a reflection nebula, which reflects the light produced by neighboring stars).
   • The Orion nebula is an emission nebula—it glows with its own light.2000 October 12, Prof. Daniel Styer, “Nebulae”, in Oberlin College Physics Department, retrieved 07 Apr 2014
   • Kitt Peak National Observatory, in Arizona, 56 miles southwest of Tucson, offers a rare opportunity to spend an entire night looking through powerful telescopes at galaxies, planetary emission nebulae and star clusters.2005 June 5, Suzanne MacNeille, “On a Dig or Through a Telescope, You Just Might Learn Something”, in New York Times, retrieved 07 Apr 2014