NASA/ESA's Hubble Space Telescope celebrates its 25th year of service on April 24, 2015. During its 25 year long mission the Hubble Space Telescope has changed our view of the Universe significantly. Some of the most ground breaking discoveries made in astronomy in the 20th century were made by Hubble. There are a lot interesting facts that the average Hubble fan may not know about this famous telescope. For example, NASA named the world's first space-based optical telescope after American astronomer Edwin P. Hubble (1889 - 1953). Dr. Hubble confirmed an "expanding" universe, which provided the foundation for the Big Bang theory. Another interesting fact -- In order to take images of distant objects, Hubble must be extremely steady and accurate. The telescope is able to lock onto a target without deviating more than 7/1000th of an arc second, or about the width of a human hair seen at a distance of 1 mile.