Scientists have discovered that a small galaxy called Tucana II has a much stronger gravitational pull than expected, which means it is likely home to a large amount of dark matter. Just as the moon orbits the Earth, many satellite galaxies are orbiting our Milky Way. Tucana II is one of them. These small galaxies, called dwarf galaxies, are thought to be relics of galaxies formed in the beginning of the universe. Tucana II is an ultrafaint dwarf galaxy about 163,000 light-years from Earth. To astronomers’ surprise, although Tucana II is small, its gravitational pull can be seen very far from its center, indicating that the dwarf galaxy has a tremendous amount of dark matter within. Based on the analyses, astronomers found that the visible, stellar mass of Tucana II is around just 3,000 times the mass of the sun, but its dark matter halo is nearly 10 million times …