Astronomy
Gravitational Lensing and Its Uses
Quick fact
The first confirmed gravitational lens was discovered in 1979 as a 'twin quasar'—two images of the same object caused by a galaxy in the foreground bending its light.
Why this is interesting
Light always travels in straight lines—except when gravity bends it. Einstein predicted this, and now astronomers use it as a giant cosmic magnifying glass to see the invisible universe.