James Webb Space Telescope revisits a classic Hubble image of over 2,500 galaxies

The James Webb Space Telescope has returned to the scene of one of the Hubble Space Telescope’s most iconic images, the Ultra Deep Field, to capture galaxies throughout cosmic history.

This new image was taken as part of the JWST Advanced Deep Extragalactic Survey (JADES), which is intent on further probing in infrared light two patches of sky that were originally imaged by Hubble: the Hubble Deep Field (1995) and the Hubble Ultra Deep Field (2004).

The deep fields were Hubble’s most intense stares into the universe, revealing the faintest galaxies at the highest redshifts that Hubble could see, galaxies that existed over 13 billion years ago and whose light has been traveling for all that time. The Hubble Ultra Deep Field, in particular, was revisited several times by Hubble, in 2009, 2012 and 2014, using the near-infrared channels on the space telescope’s Wide Field Camera 3. It shows some 10,000 galaxies detectable in an area of sky just 2.4 arcminutes square, which is less than a tenth of the diameter of the Full Moon in the night sky.

However, Hubble can only see so far. At the greatest redshifts, corresponding to galaxies that we see as they existed within a few hundred million years of the Big Bang, visible light is stretched into infrared wavelengths beyond Hubble’s capacity to see. So, to beat this limitation, the JWST has stepped up.