The resulting image consisted of 342 separate exposures, with a total exposure time of more than 100 hours, compared with typical Hubble exposures of a few hours. The observed region of sky in Ursa Major [the Big Dipper region] was carefully selected to be as empty as possible so that Hubble would look far beyond the stars of our own Milky Way and out past nearby galaxies.
The results were astonishing! Almost 3000 galaxies were seen in the image [in a speck of sky the size of a grain of sand held at arm's length!].
Scientists analyzed the image statistically and found that the HDF had seen back to the very young Universe where the bulk of the galaxies had not, as yet, had time to form stars. ..."