Why in News?

• 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.