In late 1995, the relatively new Hubble Space Telescope had been used to make a series of observations intended to detect very distant galaxies.   A target area in a very dark area of the sky devoid of any visible light, infrared, ultraviolet, and x-ray emissions was selected. 

In a tiny patch of sky equivalent to the size of a tennis ball at 100 meters, a total of 342 individual exposures were taken at different wavelengths over 5 days.  The final combined image contained over 3000 distinct galaxies, many of which were at the extreme limit of the visible universe almost 10 billion light-years away.

One of the most memorable experiences from college was the last day of an astronomy class, when the instructor put the image from the Hubble on the screen.  Bear in mind that the image was expected to have very few objects, as this was supposed to be a relatively unpopulated area of space.

Click the image for a large, high-resolution version.