What is gravitational lensing
Gravitational lensing happens when light rays are blocked by galaxies and other cosmic bodies. When light rays bend and pass through them, they are magnified and distorted. This makes hidden objects from behind appear magnified.
Cosmic objects like galaxies, nebulae and clusters of stars are are not flat. They are spherical, 3 dimensional objects. When light passes through them, it bends and passes around. This is similar to how glass lenses on earth bend light rays and magnify them.
Gravitational Lensing explained
When light from an object passes through a convex lens, it bends making the object appear big. This is called magnification. Similarly cosmic bodies like galaxies and star clusters bend light rays coming from objects behind them. Bent light rays project a magnified image of the object. They work similar to magnifying lenses. They are called gravitational lenses.
Cosmic objects are massive in size. When their mass makes light rays bend around them, the resulting image is magnified, but distorted. It often appears as a ring around the magnifying galaxy or as a halo. It can also make many images of the same object, projected around the gravitational lens.
Uses of gravitational lensing
James Webb Space Telescope uses gravitational lensing to observe cosmic objects. The very first deep field image showed us a galaxy cluster with many galaxies together acting as a gravitational lens.
The image had orange arcs splattered around. These arcs showed us galaxies and stars behind the galaxy cluster. They were hidden from the telescope by a galaxy at the center of the image , but gravitational lensing projected magnified images of them around the galaxy.
There were pairs of the same object, which was also a result of gravitational lensing.
This image (credit: NASA, ESA, CSA, STScI) has markings to illustrate gravitational lensing.
Stay tuned to read more on the latest James Webb discoveries using gravitational lensing.
