Abell 1689

This long-exposure Hubble Space Telescope image of massive galaxy cluster Abell 2744 (foreground) is the deepest ever made of any cluster of galaxies. It shows some of the faintest and youngest galaxies ever detected in space

Normally too faint for Hubble to see, these galaxies were revealed through gravitational lensing focused on a massive galaxy cluster known as Abell 1689 in the constellation Ursa Major. The cluster magnified light emitted by distant objects behind it, causing the newly discovered galaxies to appear bigger and brighter.

The Hubble exposure reveals almost 3,000 of these background galaxies interleaved with images of hundreds of foreground galaxies in the cluster. Their images not only appear brighter, but also smeared, stretched and duplicated across the field. Because of the gravitational lensing phenomenon, the background galaxies are magnified to appear as much as 10 to 20 times larger than they would normally appear. Furthermore, the faintest of these highly magnified objects is 10 to 20 times fainter than any galaxy observed previously. Without the boost from gravitational lensing, the many background galaxies would be invisible.
The Hubble exposure will be combined with images from Spitzer and NASA's Chandra X-ray Observatory to provide new insight into the origin and evolution of galaxies and their accompanying black holes.