Jonah S. Gannon

In 2015, astronomers were examining the Coma galaxy cluster and noticed something odd: huge, almost invisible "fluff balls." These galaxies are as large as our Milky Way but shine hundreds of times fainter.

The FAST radio telescope in China is a giant dish half a kilometer in diameter, nestled in a natural sinkhole among mountains.

Faint galaxies scattered across the Perseus cluster are like ghosts among their bright neighbors. They are so diffuse that distant objects shine through them, and they contain hundreds of times fewer stars than our Milky Way.