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”.
- 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.
- 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.