What is Gravitational Lensing?

About Gravitational Lensing:

• It occurs when a massive celestial body, such as a galaxy cluster, causes a sufficient curvature of spacetime for the path of light around it to be visibly bent, as if by a lens.
• The body causing the light to curve is accordingly called a gravitational lens.
• An important consequence of this lensing distortion is magnification, allowing us to observe objects that would otherwise be too far away and too faint to be seen.
• Theory:
  • Gravitational Lensing was first predicted in 1915 by Albert Einstein, which involves the bending of light by objects of great mass.
  • According to Einstein’s general theory of relativity, time and space are fused together in a quantity known as spacetime.
  • Within this theory, massive objects cause spacetime to curve, and gravity is simply the curvature of spacetime.
  • As light travels through spacetime, the theory predicts that the path taken by the light will also be curved by an object’s mass.
  • Gravitational lensing is a dramatic and observable example of Einstein’s theory in action.
  • Extremely massive celestial bodies such as galaxy clusters cause spacetime to be significantly curved. In other words, they act as gravitational lenses.
  • When light from a more distant light source passes by a gravitational lens, the path of the light is curved, and a distorted image of the distant object — maybe a ring or halo of light around the gravitational lens — can be observed.

 

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Q1) What is Supernova?

A supernova is what happens when a star has reached the end of its life and explodes in a brilliant burst of light. Supernovas can briefly outshine entire galaxies and radiate more energy than our sun will in its entire lifetime.

Source: Astronomers have captured a background supernova being gravitationally lensed by a foreground galaxy.