Phase of the Moon, circa 1857. This view of the Moon was obtained using an early type of photographic print known as the salt print. When produced from glass negative plates, the result was known as a crystalotype. This one was produced by US photographer John Adams Whipple (1822-1891), in collaboration with US photographer James Wallace Black (1825-1896). The mapping of the Moon with telescopes started with Galileo in 1610, and then developed further over the centuries as telescopes improved. The far side of the Moon was not observed until the era of spaceflight. This example was produced using telescopes at Harvard College Observatory, Massachusetts, USA.