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Mahesh

03/08/22 13:12 PM IST

Gravitational Lensing

In News 
  • USA's space agency NASA had launched James Webb Space Telescope (JWST) in 2021, which will use a natural phenomenon called “gravitational lensing” to carry out astronomical observations.
Gravitational Lensing
  • The phenomenon of gravitational lensing occurs when a huge amount of matter, such as a massive galaxy, cluster of galaxies or a black hole, creates a gravitational field that distorts and magnifies the light from objects behind it.
  • Gravitational lensing is based on Einstein's theory of general relativity (Mass bend light).
  • Normal lenses such as the ones in a magnifying glass work by bending light rays that pass through them in a process known as refraction, in order to focus the light somewhere else.
  • Similarly, the gravitational field of a massive object causes light rays passing close to that object to be bent and refocused somewhere else.
  • The more massive the object, the stronger its gravitational field and hence the greater the bending of light rays - just like using denser materials to make optical lenses results in a greater amount of refraction.
  • In effect, gravitational lenses act like natural cosmic telescopes.
  • The effect allows researchers to study the details of early galaxies too far away to be seen otherwise with even the most powerful space telescopes.
  • However, gravitational lensing is very rare as it requires a distant star, black hole and the observer on earth to be well-aligned.
  • Also, it can help astronomers to know about black holes, dark matter, etc.
Source- Indian Express 

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