Distant Galaxies Lensed by Cluster J0717
J0717 isn't just a large cluster of galaxies; astronomers are using it like a giant telephoto lens attachment to study the very distant, very faint universe. This new infrared view from NASA's Spitzer Space Telescope will be used in tandem with observations from other major NASA observatories to glimpse the universe's very first galaxies. Called Frontier Fields, the project is a collaboration with the Hubble Space Telescope and the Chandra X-ray Observatory.
The faintness of the earliest, most distant galaxies makes studying them a challenge, even with long, deep exposures. Frontier Fields, however, can spot these primordial galaxies courtesy of foreground clusters of galaxies, whose gargantuan mass and gravity form cosmic "zoom lenses."
The clusters warp space around them, magnifying background galaxies. The cluster in this image, known as J0717, is the grouping of bright objects near the center of the field, while examples of the very distant background galaxies appear as distorted arcs at the center of the two circular call-outs.