James webb deep field

The James Webb Space Telescope's deep field revealed thousands of never-before-seen galaxies, 4.6 billion light-years away.

About this subject

The James Webb Space Telescope's deep field is a composite image capturing the galaxy cluster SMACS 0723, located approximately 4.6 billion light-years away. It was the first scientific image released by NASA on July 11, 2022, during a live broadcast with President Joe Biden. The region, appearing nearly empty to the naked eye, reveals thousands of distant galaxies thanks to the gravitational lensing effect caused by the foreground cluster's mass.

The image covers an area of the sky equivalent to a grain of sand held at arm's length. The most distant objects appear red due to cosmological redshift. JWST, with its 6.5-meter mirror and infrared instruments, can see galaxies that formed less than 600 million years after the Big Bang, impossible for earlier telescopes. The Webb Deep Field is a direct successor to the famous Hubble Deep Field but with far greater sensitivity and resolution.

This image is not only visually stunning but also a scientific treasure. Astronomers have already identified hundreds of high-redshift candidate galaxies, some with unexpectedly high masses for such early times. Subsequent data revealed a galaxy with a redshift of 13.2, corresponding to just 400 million years after the Big Bang. Detailed study of these objects helps understand cosmic reionization and the formation of the first stars.

Remarkably, the image was obtained in just 12.5 hours of exposure, whereas the Hubble Deep Field required over 10 days. JWST is positioned at the L2 Lagrange point, 1.5 million kilometers from Earth, ensuring thermal and orbital stability for continuous observations. The Webb Deep Field represents a new milestone in observational astronomy, revealing an ever more distant and primordial universe.

Frequently Asked Questions

What is the James Webb Deep Field?

It is the first scientific image released by the James Webb Space Telescope, showing galaxy cluster SMACS 0723 with thousands of distant galaxies revealed by gravitational lensing.

How can James Webb see such ancient galaxies?

It uses a 6.5-meter mirror and infrared instruments to capture light from objects over 13 billion light-years away, with exposures as short as 12.5 hours.

What makes the Webb Deep Field different from Hubble's?

Webb observes in infrared, sees more distant and primitive galaxies, and required much shorter exposure: 12.5 hours versus over 10 days for Hubble.