Caption: "Galaxies abound in this spectacular Hubble Space Telescope (HST, 1990--2040?) image; spiral galaxies (that is their spiral arms) swirl in all colours and orientations and fuzzy elliptical galaxies can be seen speckled across the frame as softly glowing smudges on the sky. Each visible speck of a galaxy is home to countless stars A few stars closer to home shine brightly in the foreground (i.e., foreground stars in the Milky Way showing diffraction pattern points from overexposure because they are bright compared to every else in the image), while a massive galaxy cluster (catchily named RXC J0142.9+4438, AKA CIZA J0142.9+4438) nestles at the very centre of the image; an immense collection of maybe thousands of galaxies, all held together by the relentless force of gravity.

Galaxy clusters are some of the most interesting astronomical objects in the observable universe. They are the nodes of the cosmic web that permeates the observable universe. To study them is to study the organisation of matter on the grandest of scales. Not only are galaxy clusters ideal subjects for the study of dark matter and dark energy, but they also allow the study of farther-flung galaxies. Their immense gravitation means they distort the spacetime around them, causing them to act like giant gravitational lenses. The light of background galaxies is warped and magnified as it passes through or around the galaxy cluster, allowing astronomers insight into the distant and therefore late early universe (i.e., Dark Ages and large-scale structure emergence era, cosmic time ∼ 370 kyr--1 Gyr). This image was taken by the Hubble Space Telescope's (HST, 1990--2040?) Advanced Camera for Surveys (2002--) and Wide-Field Camera 3 (2009--) as part of an observing programme called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the James Webb Space Telescope (JWST, 2021--2041?) to study."

(Somewhat edited.)