Galaxy cluster Abell 2218 acts as a powerful lens, magnifying all galaxies lying behind the cluster core. The lensed galaxies are all stretched along the cluster's center and some of them are multiply imaged. Those multiple images usually appear as a pair of images with a third - generally fainter - counter image, as is the case for the very distant object. The color of the lensed galaxies is a function of their distances and types. The orange arc is an elliptical galaxy at moderate redshift (z = 0.7). The blue arcs are star-forming galaxies at intermediate redshift (z = 1-2.5). The newly discovered star-forming galaxy at about redshift 7 appears as a pair of very faint, very red arcs near the blue galaxy left of center.
ESA, NASA, J.-P. Kneib (Caltech/Observatoire Midi-Pyrénées) and R. Ellis (Caltech)