Replacing the Hubble Ultra-Deep Field and Deep Field and before it, the eXtreme Deep Field, or XDF, is the deepest-ever view of the universe. Combining a decade of NASA Hubble Space Telescope photographs of a patch of sky at the center of the original Hubble Ultra Deep Field, the XDF is a tiny fraction of the angular diameter of the full moon.
The image contains about 5,500 galaxies. The faintest galaxies are one ten-billionth the brightness of what the human eye can see.
The infrared vision of NASA’s future James Webb Space Telescope, the successor of Hubble, will be aimed at the XDF. The Webb telescope will find far fainter galaxies that existed when the universe was only a few hundred million years old. Because of the expansion of the universe, light from this distant past is stretched into longer, infrared wavelengths.
The Webb telescope’s infrared vision is ideally suited to push the XDF even deeper, into a time when the first stars and galaxies formed and filled the early “dark ages” of the universe with light.