Check the current issue of the SCIENCE journal, where Showalter and Lissauer present actual photos of two newly discovered moons of Uranus. The equipment used was the Hubble mirror and the ASC (Advanced Survey Camera) in high resolution mode with a pixel scale of 0.025 arc seconds and a "point spread function several times that size". After repeated long exposures and aligning and "coadding" pixels they were able to detect two tiny moons (which they named "Cupid " and "Mab") which are only 18 and 12 Km in diameter respectively. That is, for Mab they 'resolved' an object less than 8 miles in diameter from 1.7 billion (with a 'b') miles away! Fascinating!