Calendario dell’Avvento: 18 dicembre

Small, dim galaxies appear to flit like moths around a radiant street light in this image. The brilliant central object is a supergiant elliptical galaxy, the dominant member of a galaxy cluster with the mouthful of a name MACSJ1423.8+2404. This great swarm of galaxies is located about five billion light-years away in the constellation Boötes (the Herdsman). The gentle arcs surrounding the central galaxy are distorted views of even more distant galaxies. The gravity of the closer large galaxy creates a gravitational lensing effect, distorting and amplifying the light that passes close by on its way to an observer, like us. (ESA/Hubble and NASA) More