星系壁纸
by NASA, ESA, A. Nierenberg, T. Treu
NASA Image Library · 公有领域（Public Domain）
关于这张图
Each of these Hubble Space Telescope snapshots reveals four distorted images of a background quasar (an extremely bright region in the center of some distant galaxies) and its host galaxy surrounding the core of a foreground massive galaxy. The gravity of the massive foreground galaxy acts like a magnifying glass by warping the quasar's light in an effect called gravitational lensing. Quasars are extremely distant cosmic "streetlights" produced by active black holes. Such quadruple images of quasars are rare because of the nearly exact alignment needed between the foreground galaxy and backgr…
