Gravitational Wave Observations

Gravitational Lensing

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Dark Matter, Gravitational Lensing

Mains level : Gravitational Lensing


  • Using NASA’s James Webb Space Telescope as a sort of time machine, researchers plan to investigate how new stars are born.
  • For this, they will take the help of a natural phenomenon called “gravitational lensing”.

Gravitational Lensing

  • The phenomenon occurs when a huge amount of matter, such as a massive galaxy or cluster of galaxies, creates a gravitational field that distorts and magnifies the light from objects behind it, but in the same line of sight.
  • In effect, these are natural, cosmic telescopes; they are called gravitational lenses.
  • These large celestial objects will magnify the light from distant galaxies that are at or near the peak of star formation.
  • 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.

How it works?

  • Normal lenses such as the ones in a magnifying glass or a pair of spectacles work by bending light rays that pass through them in a process known as refraction, in order to focus the light somewhere (such as in your eye).
  • Gravitational lensing works in an analogous way and is an effect of Einstein’s theory of general relativity – simply put, mass bends light.
  • The gravitational field of a massive object will extend far into space, and cause light rays passing close to that object (and thus through its gravitational field) 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.

TEMPLATES Programme

  • The Milky Way today forms the equivalent of one Sun every year, but in the past, that rate was up to 100 times greater.
  • NASA now plans to look billions of years into the past in order to understand how our Sun formed.
  • The programme is called Targeting Extremely Magnified Panchromatic Lensed Arcs and Their Extended Star Formation, or TEMPLATES.
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