Cleomenus taught that she shone by reflected light.
Berose the Chaldean discovered that the duration of her movement of rotation was equal to that of her movement of revolution, and he thus explained why the moon always presented the same side.

Lastly, Hipparchus, 200 years before the Christian era, discovered some inequalities in the apparent movements of the earth's satellite.
These different observations were afterwards confirmed, and other astronomers profited by them.

Ptolemy in the second century, and the Arabian Aboul Wefa in the tenth, completed the remarks of Hipparchus on the inequalities that the moon undergoes whilst following the undulating line of its orbit under the action of the sun.

Then Copernicus, in the fifteenth century, and Tycho Brahe, in the sixteenth, completely exposed the system of the world and the part that the moon plays amongst the celestial bodies.
At that epoch her movements were pretty well known, but very little of her physical constitution was known.

It was then that Galileo explained the phenomena of light produced in certain phases by the existence of mountains, to which he gave an average height of 27,000 feet.
After him, Hevelius, an astronomer of Dantzig, lowered the highest altitudes to 15,000 feet; but his contemporary, Riccioli, brought them up again to 21,000 feet.
Herschel, at the end of the eighteenth century, armed with a powerful telescope, considerably reduced the preceding measurements.