Image: NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)
The image (above) of Pandora's Cluster shows hundreds of galaxies in a large group, as well as images of galaxies much farther behind the cluster. The massive galaxy cluster serves as a gravitational lens to magnify the galaxies behind it. For reference, see the image below, which shows only the galaxies that are part of Pandora's cluster.
Most of the lensed galaxies in the top image are distorted into streaks and arcs. Several galaxies appear multiple times, with their light traveling several distinct paths through the irregular gravitational lens of the galaxy cluster. This image uses both visible and infrared light, and is part of the first data released by the Frontier Fields project.
Image: Dan Coe (STScI)