In other words, we don't know if completely dark, star-free halos exist," Nadler told Space.com. "A starless or 'dark' dark matter halo would have no galaxy at its center." Previously, Nadler ...

For the past several hours I’ve struggled to keep up as she leads me deeper into a frozen underworld known as Dark Star. Larisa, a 30-something veteran caver from the Ural Mountains, moves with ...