A massive and extremely remote celestial object,
emitting exceptionally large amounts of energy,
and typically having a starlike image in a telescope.
It has been suggested that quasars contain massive black holes
and may represent a stage in the evolution of some galaxies.

  • most intense sources of light in the Universe, quasars are no bigger than the Solar System, but they glow with the brightness of 100 galaxies.
  • quasars are the most distant known objects in the Universe – even the nearest is a billion light years away.
  • most distant quasar is on the very edge of the known Universe, 13 billion light years away.
  • some quasar are so far away that we see them as they were when the Universe was still in its infancy – less than 10 percent of its current age.
  • quasar is short for Quasi-Stellar Radio Source (see below) – this comes from the fact that the first quasars were detected by the strong radio signals they give out, and also because quasars are so small and bright that at first people though they looked like stars.


  • less than 10 percent of the 100,000 quasars now known actually beam out radio signals.
  • the brightest quasar, 3C 273, is 2.5 billion lights years away.

3C 273’s quasar

  • quasars are at the heart of some galaxies called ‘active galaxies’.
  • the energy used by quasars comes from a black hole at their core, which draws in matter ferociously.
  • the black hole in a quasar may have same mass as 100 million suns.

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