test 1 Astronomy - May 2018 USA | Page 74

BREAK THROUGH In the hub with Hubble Perched above Earth’s turbulent atmosphere, the Hubble Space Telescope can resolve fine details in crowded fields. This view of the Milky Way’s central bulge could be Exhibit A. During the past nine years, scientists have used Hubble’s unique capabilities to track about 10,000 Sun-like stars in this congested region. They found that the younger stars — those richer in elements heavier than hydrogen and helium — orbit the galaxy’s center faster than their older cousins. The researchers suggest that these youthful interlopers could be relics of smaller galaxies that the Milky Way cannibalized. NASA/ESA/T. BROWN (STS C I) 74 A ST R O N O M Y • MAY 2018