Happy Birthday Andrea Ghez! The UCLA astronomer was born in New York City in 1965. For more than two decades Ghez has used the Keck telescope in Hawaii to study the bustling center of the Milky Way. In the 1970s astronomers had proposed that supermassive black holes might lurk at the centers of ultrabright galaxies called quasars; Ghez wondered whether ordinary galaxies like our own might also host gargantuan black holes. So she and her colleagues analyzed the motions of stars in the galactic center and determined how much mass was packed within the stars' orbits. By 1997 Ghez had compiled compelling evidence that a supermassive black hole resides in the galactic center; now the evidence is overwhelming. That black hole, Sagittarius A*, is more than 4 million times as massive as the Sun. Ghez has won many awards, including a MacArthur Fellowship in 2008. (Photo courtesy of the John D. and Catherine T. MacArthur Foundation, CC BY 4.0)
