Cosmic mystery: Why are many galaxies dark?
They have so few stars that their existence was unknown until 2015
Christopher Crockett
Apr 18, 2017 — 7:10 am EST
Dark galaxies can’t be seen with the unaided eye. But the multi-lensed Dragonfly telescope (shown) in New Mexico can spot them. It has triggered a hunt for dim galaxies in our cosmic neighborhood.
P. VAN DOKKUM
Galaxies are home to vast communities of stars, some likely numbering in the hundreds of millions. But not all of these stellar neighborhoods glow with starlight. Some galaxies as wide as the Milky Way are all but dark. Unlike Andromeda and other well-known galaxies, these dark beasts have no grand spirals of stars and gas wrapped around a glowing core. Nor are they radiant balls of densely packed suns. Instead, these may amount to no more than a wisp of starlight barely illuminating some tenuous blob.
https://www.sciencenewsforstudents.org/article/cosmic-mystery-why-are-many-galaxies-dark
