A Lightless Galaxy: Scientists Discover a Starless, Spinning Ghost

Astronomers may have just stumbled across a ghost galaxy hiding in plain sight — a small, starless, fast-moving cloud of gas that checks all the boxes for what’s known as a “dark galaxy.” And if the discovery holds up, it could help plug one of cosmology’s most puzzling holes: the mysterious “missing satellite” problem. The team’s research, published today in Science Advances, describes AC G185.0–11.5, a compact hydrogen cloud tucked inside a larger high-velocity cloud (HVC) known as AC-I. The cloud was spotted by an international research team using China’s huge FAST radio telescope. While HVCs are known to zoom around at speeds beyond that of our Milky Way’s rotation, most are relatively featureless gas blobs. But the recently spotted gas cloud is different: it spins. FAST’s ultra-sensitive observations revealed a clear rotational pattern in the cloud, whose gas is arranged in a disk shape — the kind of structure you’d expect from a dwarf galaxy. But something’s amiss: there’s no s ... Read full article.