This image combines data from ALMA and the Hubble Space Telescope. Shown in red is a distant, background galaxy, being distorted by the gravitational lens effect produced by the galaxy in the foreground. That galaxy is shown in blue and was measured by Hubble. The background galaxy appears warped into a so-called Einstein ring: a circle of light around the foreground galaxy.
Astronomers first spotted signs of the distant galaxies with the South Pole Telescope, and then used ALMA to zoom in on them in greater detail. They were surprised to find that many of these galaxies were farther away than expected.