Sebastiano Cantalupo, of the University of California, Santa Cruz, and his colleagues may have become the first people ever to spot “dark galaxies”, the antediluvian ancestors of the bright islands that contain almost all of the stars in the modern universe, and of which Earth’s own Milky Way is one. Despite their name, dark galaxies are not as tenebrous as other “dark” astronomical phenomena. Unlike dark energy or exotic dark matter—so called because, since they do not interact with photons of electromagnetism, their presence can only be discerned through their gravitational effects—they are made up of humdrum hydrogen and helium gas. But they are relatively small, and their weak gravity means their gas is so dispersed that stars condense out of it only very slowly. Some characteristics of bigger, brighter, modern galaxies—for example, the relationship between a galaxy’s mass and its star-formation rate—could be explained if there are sources of gas feeding them. Dark galaxies could fit the bill.

Cosmology: Glow in the dark | The Economist. Aside from the general interest of the discovery, I love the concept of “modern galaxies.” I’m hoping that there are also Modernist galaxies, that there’s a galactic Picasso out there, a galactic Joyce.