The James Webb Space Telescope (JWST) is currently the most powerful telescope operating in space, allowing it to see a vast distance into the universe. Launched in December 2021, JWST can detect infrared and near-infrared wavelengths, which are invisible to humans but can be felt as heat.
This technology is crucial for astronomers hoping to peer into the deepest depths of the universe. However, even the powerful new Vera C. Rubin Telescope, recently activated in Chile, cannot see this far into space due to anomalous obstructions like dust.
When the universe began, it was condensed into a hot mash of particles. As it expanded and cooled, the first stars and galaxies coalesced. The earliest galaxies we can see are around 13.7 billion years old, just over a hundred million years after the Big Bang.
The JWST has proven itself capable of seeing 98% of the way back to the Big Bang, exceeding hopes and expectations for most astronomers involved in its early planning. This is made possible by its large primary mirror, which measures 21.3 feet (6.5 meters) in diameter.
Astronomers bypass complications when measuring how far a telescope can see into space by accounting for the expansion of the universe and the finite speed of light. They measure the redshift of distant celestial bodies, which becomes greater as the universe expands. The JWST’s advanced technology allows it to detect these subtle changes in light.
While the JWST is currently the champion in peering deep into our cosmic past, rivals are on the horizon. China is building a space telescope that will enable it to capture more light frequencies than JWST, allowing it to withdraw greater information from the cosmos.
Source: https://www.livescience.com/space/how-far-can-the-most-powerful-telescope-see-into-space