爱因斯坦的引力透镜十字架
2021年10月17日 The Einstein Cross Gravitational Lens Image Credit & License: J. Rhoads (Arizona State U.) et al., WIYN, AURA, NOIRLab, NSF Explanation: Most galaxies have a single nucleus — does this galaxy have four? The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this image. The cen...