Hubble Space Telescope has been peering deep into the universe for almost a quarter of a century. Among many accomplishments, its observations have demonstrated that the universe is expanding faster as it ages. That the universe is expanding at all was established by the telescope’s namesake, Edwin Hubble, who was born 125 years ago this week. Hubble earned his doctorate in astronomy during World War I, then joined the army and was sent to France. When he came home, a job was waiting for him at Mount Wilson Observatory in California. The observatory had just built the world’s largest telescope, and Hubble used it to study the whorls of matter known as nebulae. At the time, some thought these objects were all inside the Milky Way, while others thought that some of them were separate galaxies of stars far beyond the Milky Way. Hubble discovered a pulsating star in the Andromeda Nebula. The length of the star’s pulses revealed its true brightness, which Hubble used to calculate its distan
