A gorgeous new portrait of an ancient star cluster reveals an unexpected imperfection: a visible gap in the brightness of its stars.
The stunning image, taken by the European Space Agency’s (ESA) Euclid space telescope, captures NGC 6397 — one of the closest globular clusters to Earth. NGC 6397 is a glittering swarm of hundreds of thousands of stars packed tightly together, but when astronomers took a closer look, they discovered something unusual hidden within the sparkles.