Andrew B. Pace

On the outskirts of the Milky Way, tiny stellar systems hide, so faint that even powerful telescopes barely spot them. Until recently, astronomers knew almost nothing about these objects, dubbed ultra-faint compact satellites.

The night sky is like an ocean: the longer you stare, the more faint lights you notice in the depths. That's how astronomers, peering into the outskirts of the Milky Way, found Aquarius IV — a tiny stellar system that had been hiding in the dark until now. The system was spotted in images from an early survey by the future Vera Rubin Observatory.