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photon sphere

photon sphere noun: of a black hole, a spherical limit around a black hole at such distance that any photon meeting it tangentially is constrained to travel in a circular orbit; (more loosely) the region between this limit and the event horizon.

Noun

photon sphere (plural photon spheres)

  1. Of a black hole, a spherical limit around a black hole at such distance that any photon meeting it tangentially is constrained to travel in a circular orbit; (more loosely) the region between this limit and the event horizon.
    • The radius of the photon sphere is also the lower bound for any stable orbit.
    • For a Schwarzschild (non-spinning) black hole, the radius of the photon sphere is 1.5 times the Schwarzschild radius.

Examples of photon sphere in a sentence

  • The redshift of light leaking outward from the photon sphere is #92;sqrt#123;3#125;-1#61;0.732.2000, Edward Harrison, Cosmology, 2nd edition, Cambridge University Press, page 250:
  • In particular, there are two photon spheres, in contrast with the one photon sphere around a stationary Schwarzschild black hole.2015, Katherine Blundell, Black Holes: A Very Short Introduction, Oxford University Press, page 44:
  • The region inside the photon sphere has a diameter of 1.5× Schwarzschild diameter D(s), but due to the curvature, this region gets magnified to 2.6× D(s).2022, Wouter Schmitz, Understanding Relativity, Springer, page 277:

Synonyms of photon sphere

Forms of photon sphere

pluralphoton spheres

Origin of photon sphere

From photon + sphere.

Questions about photon sphere

What does photon sphere mean?
Photon sphere means of a black hole, a spherical limit around a black hole at such distance that any photon meeting it tangentially is constrained to travel in a circular orbit; (more loosely) the region between this limit and the event horizon.
How do you use photon sphere in a sentence?
The redshift of light leaking outward from the photon sphere is #92;sqrt#123;3#125;-1#61;0.732.
What part of speech is photon sphere?
Photon sphere is a noun.
What is the plural of photon sphere?
The plural of photon sphere is photon spheres.

Words near photon sphere in the dictionary

  1. photon circles
  2. photon mapping
  3. photon mappings
  4. photon sail
  5. photon sails
  6. photon sphere
  7. photon spheres
  8. photon tunnelling
  9. photonastic
  10. photonasty
  11. photonecrosis

Source and license

Adapted from Wiktionary: photon sphere (page history and authors). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

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