A sweeping barred spiral galaxy marks the spot in this image, but the real treasure is the gravitational lens in the lower-right corner, where a distant background galaxy is being magnified and distorted by the gravity of a closer galaxy.

This observation is one of many gravitational lensing images taken by NASA’s Hubble Space Telescope in preparation for science with the new Nancy Grace Roman Space Telescope .

Gravitational lensing occurs when the mass of a foreground object – such as a galaxy – warps spacetime, causing light to bend, distort, and magnify as it passes around the object, similar to a giant lens in space. Lenses like this occur when a precise chance alignment takes place between the foreground and background galaxies, causing light from the background galaxy to curve around the foreground galaxy.

In this image, the gravitational lens features a foreground elliptical galaxy that is about 4.5 billion light-years away.…