English: About 3.5 million years ago—just a blink of an eye in cosmic time—a tremendous explosion rocked the center of our galaxy. Our distant hominid ancestors, already afoot on the African plains, likely would have seen the resulting flare as a ghostly glow high overhead in the night sky. Now, astronomers using NASA's Hubble Space Telescope's unique capabilities have uncovered even more clues to this cataclysmic explosion.