A grain of sky. Thousands of galaxies.

Webb’s First Deep Field was unveiled on 11 July 2022. The target was the galaxy cluster SMACS 0723; thousands of galaxies appeared within a patch of sky NASA compared with a grain of sand held at arm’s length. That comparison describes angular size: how much sky the frame covers. It says nothing about the physical size of a galaxy. The cluster itself appears as it was 4.6 billion years ago, while other galaxies lie in front of and behind it. The result is not one slice of the universe at a single moment. A compact rectangle brings together light that has travelled for very different lengths of time.

The mass of the foreground cluster bends the paths of light from galaxies behind it. This gravitational lens can magnify and distort their appearances; it can also produce multiple images of one source. In a companion July 2022 release, ESA showed two stretched arcs with matching spectra, indicating two images of the same galaxy. Their light was emitted 9.3 billion years ago. The match required more than a visual resemblance: spectra spread light into its component wavelengths so researchers can compare its features. A pretty curve therefore opens a specific scientific problem. Is this a separate object, or another route by which the same object’s light reached us?

The published near-infrared view combines NIRCam observations through different filters, totalling 12.5 hours. Infrared light lies beyond human vision. Webb’s image processors map shorter observed wavelengths towards visible blue and longer ones towards red, with intermediate colours between them. The colours make differences in the measurements available to our eyes; they are not the colours a visitor would see through a window. This distinction gives the image more meaning. You are looking at both a remote scene and a deliberate way of presenting information about it. The telescope supplies measurements, and the composite makes some relationships among those measurements easy to notice.

Return to the official deep field and choose a small region instead of scanning the whole frame. Separate the bright spiked stars from the extended shapes, follow one curved arc, then look for the smaller marks around it. Shapes provide clues, but the spectra example shows where eyesight needs help. Similarity can suggest a question; additional measurements test it. That is the lasting interest of this 2022 release. Its crowd of galaxies changes our sense of scale, while its companion data show how a striking image becomes research. The illustration in this edition is an editorial study inspired by that encounter. The linked institutional pages contain the actual telescope images and their credits.