This image covers a relatively small area of sky -- only one tenth the diameter of the full moon -- in the constellation Hercules.
The faint blue galaxies seen here at distances estimated to range from three to eight billion light-years have a wide variety of shapes suggesting that galaxy collisions and other interactions were more common in the past. They are blue because the great number of young, hot, and blue stars.
It required a total of 48 orbits around the Earth (amounting to roughly one day of exposure time) to make the observation and detect objects about four billion times fainter than the unaided eye can see (30th magnitude).
HUBBLE'S "DEEP" VIEW OF EARLY UNIVERSE
HELPS SOLVE THE FAINT BLUE GALAXY MYSTERY
(R. Windhorst. 24-7-1995)