In March 1610 Galileo published his book Sidereus Nuncius [The Starry Messenger] containing the first astronomical observations ever made with a telescope. Among other wonders in this masterwork are the first drawings and descriptions of mountains on the moon:
…very many bright points [that] appear within the dark part of the Moon, entirely separated and removed from the illuminated region and located no small distance from it.
This quote is from Sidereus Nuncius translated by Albert Van Helden (Chicago, 1989). For an excellent discussion of Galileo see Beautiful Evidence by Edward R. Tufte (Graphics Press, 2006).
At center left in this photograph we see evidence of mountains just as Galileo described. Montes Harbinger, a mountain range with peaks 2.5 km (7600 ft) above Mare Imbrium, appears as two bright spots as the mountain tops catch the sunlight while all below remains in darkness. The prominent crater Copernicus is seen at lower right.
First quarter moon photographed at Carlisle, Massachusetts on October 2, 2006
Questar 3.5″ telescope using positive projection with 16 mm Brandon eyepiece and Nikon D100, guided, approx. 1/2 sec