Space bends under mass like a trampoline mat under a weight. This curved path of light, predicted by Albert Einstein, is called spacetime curvature. When aligned just right, a massive object acts as a cosmic magnifying glass, producing multiple images of a distant source — an Einstein cross.

Astronomers found such a cross near galaxy HerS-3, shrouded in cosmic dust and furiously birthing stars. Its light is bent by a foreground group of galaxies. Comparing colors, light analysis, confirmed that all five spots in the sky are twin copies. But trying to recreate the image using only glowing matter failed. Only by adding invisible dark matter, like an unseen weight on that same trampoline, did the model match the observations. The gravitational field revealed the presence of a colossal hidden mass where nothing shines.

Now HerS-3 has become a natural telescope, letting us peer inside a distant galaxy. We’re looking back to when the universe was just 3 billion years old — long before the Sun was born. The cross not only magnifies the stellar factory of the past but also weighs dark matter: the lens contains tens of times more of it than ordinary matter.