The Hubble Deep Field is the result of a series of observations by the Hubble Space Telescope of a small region of the northern celestial hemisphere. It was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over 10 consecutive days between December 18 and December 28, 1995. The field is small enough that only a few foreground stars in the Milky Way lie within it; thus, almost all of the 3,000 objects in the image are galaxies, some of which are among the youngest and most distant known. By revealing such large numbers of very young galaxies, the HDF has become a landmark image in the study of the early universe, and it has been the source of almost 800 scientific papers since it was created. Three years after the HDF observations were taken, a region in the south celestial hemisphere was imaged in a similar way and named the Hubble Deep Field South. The similarities between the two regions strengthened the belief that the universe is uniform over large scales and that the Earth occupies a typical region in the universe (the cosmological principle).