The Hubble Ultra Deep Field Looks Back in Time

On March 9, 2004, astronomers unveiled the Hubble Ultra-Deep Field, providing an unprecedentedly clear view of the distant cosmos. Collected by the Hubble Space Telescope between September 2003 and January 2004, the image captured a tiny patch of space located in the southern-hemisphere constellation Fornax. This narrow parcel accounted for approximately one twenty-six-millionth of the total sky, measuring 2.4 arcminutes along each edge. Despite its minuscule angular size, roughly one-tenth the diameter of a full moon as viewed from Earth, the exposure revealed an estimated 10,000 galaxies spanning billions of years of cosmic history.

The initiative built upon the groundwork laid by earlier projects, including the original Hubble Deep Field and surveys of the southern celestial hemisphere. Following the installation of the Advanced Camera for Surveys in 2002, astronomers recognized that new instrumentation could peer beyond previously observed limits. During a workshop held at the Space Telescope Science Institute that year, Massimo Stiavelli proposed an ultra-deep survey to examine celestial bodies linked to cosmic reionization. Institute director Steven Beckwith allocated four hundred orbits of discretionary telescope time to the undertaking, appointing Stiavelli to lead the team that planned and executed the campaign.