Gazing into the universe is like looking into a funhouse mirror. That's because gravity warps the fabric of space, creating optical illusions.

Many of these optical illusions appear when a distant galaxy's light is magnified, stretched, and brightened as it passes through a massive galaxy or galaxy cluster in front of it. This phenomenon, called gravitational lensing, produces multiple, stretched, and brightened images of the background galaxy.

This phenomenon allows astronomers to study galaxies so distant they cannot be seen other than by the effects of gravitational lensing. The challenge is in trying to reconstruct the distant galaxies from the odd shapes produced by lensing.

But astronomers using the Hubble Space Telescope stumbled upon one such odd shape while analyzing quasars, the blazing cores of active galaxies. They spotted two bright, linear objects that appeared to be mirror images of each other. Another oddball object was nearby.

The features so befuddled the astronomers that it took them several years to unravel the mystery. With the help of two gravitational-lensing experts, the researchers determined that the three objects were the distorted images of a faraway, undiscovered galaxy. But the biggest surprise was that the linear objects were exact copies of each other, a rare occurrence caused by the precise alignment of the background galaxy and the foreground lensing cluster.

Lee esta historia en español.