nebula

Meanings

1. 1
   noun

   an interstellar cloud of gas and dust, often associated with the formation or death of stars

   Ultraviolet radiation from young stars causes the Orion Nebula to glow.

2. 2
   noun

   historically, any diffuse celestial object seen as a cloudy patch; the term once included objects now known to be galaxies

   Early astronomers called Andromeda a spiral nebula before establishing that it is a separate galaxy.

3. 3
   noun

   in ophthalmology, a faint opacity or scar of the cornea

   The ophthalmologist described the faint corneal opacity as a nebula.

Appears in

Simplified etymology

Nebula comes from classical Latin nebula, “mist, fog, or cloud.” It had several medical uses in Middle English. Its modern astronomical use, referring to the cloudlike appearance of a very distant galaxy, was first recorded by Edmond Halley in 1718.

Borrowed from Latin nebula ("mist, cloud"). Early telescopic observers applied the cloud image to unresolved fuzzy objects in the sky. Modern astronomy reserves nebula mainly for interstellar gas and dust, while former "spiral nebulae" such as Andromeda are recognized as galaxies.

Topics

External links

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• Cambridge Dictionary
• Wiktionary