Page:Popular Science Monthly Volume 66.djvu/347

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Galileo in the Sidereus Nuncius (1610) gives this account of the invention of the telescope:

On the title page of his book the telescope is described as 'lately invented by him.' This claim Galileo does not make, but in subsequent years it was charged by his enemies that he claimed credit not his due, and the charge perpetually reappears. The amazing discoveries of this memorable year are enumerated on the title page in question.

The surface of the moon was covered with brilliant and dark areas as the peacock's tail with spots. Perhaps the moon has an atmosphere, he says. The heights of lunar mountains can be fixed by measuring their shadows. The ashy-light of the moon ('old moon in the new moon's arms') is perhaps caused by a lunar twilight. He gives Leonardo da Vinci's explanation also—the true one—that it is caused by earth-light reflected to the moon and back to us. The stars appear as points of light, the planets as small discs. The telescope brings