Findings suggest the first galaxies in the universe were more massive than previously thought Astronomers have detected an extended dark matter halo around an ancient dwarf galaxy. February 22, 2021 The Milky Way is surrounded by dozens of dwarf galaxies thought to be relics of the first galaxies in the universe. Among the most primitive of these galactic fossils is Tucana II -- an ultrafaint dwarf galaxy that is about 50 kiloparsecs, or 163,000 light years, from Earth. Now astrophysicists at the Massachusetts Institute of Technology have detected stars at the edge of Tucana II, in a configuration that is surprisingly far from its center but is caught up in the tiny galaxy's gravitational pull. This is the first evidence that Tucana II hosts an extended dark matter halo -- a region of gravitationally bound matter the researchers calculated to be three to five times more massive than scientists had estimated.