Gravitational lensing around a black hole can bend light from background objects into circular or arc-shaped rings, creating visually stunning effects. These rings reveal mass distribution and spacetime curvature.
It matters because it allows astronomers to study invisible mass, like dark matter, and black hole gravity.
It also helps test Einstein’s predictions in extreme conditions.
Light from distant stars can form rings around black holes due to gravity.
[ESA, esa.int]