Left: There are some 10,000 galaxies in the Hubble Ultra Deep Field (HUDF), but astronomers have found one, designated HUDF-JD2, that is among the most distant. It's also surprisingly massive and mature for its age. Right: HUDF images are the deepest ever made at optical (top) and near-infrared (center) wavelengths. The object (circled) appears faintly in Hubble's near-infrared image. The Spitzer Space Telescope easily detects the galaxy at longer infrared wavelengths (bottom).
NASA / ESA / B. Mobasher (STScI/ESA)