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Astronomy

Gravitational Lensing and Its Uses

Quick fact

Gravitational lensing can create multiple images of the same distant galaxy, sometimes forming a perfect ring of light called an Einstein ring. The first such ring was discovered in 1987.

Why this is interesting

Imagine a cosmic magnifying glass so powerful it can reveal galaxies billions of light-years away, while also revealing the invisible skeleton of the universe. How can empty space act like a lens?