The Sidereal Messenger of Galileo Galilei by Galileo Galilei and Johannes Kepler

“In this Discussion Kepler gives reasons for accepting Galileo’s observations—although he was not able to verify them from want of a telescope—and entirely supports Galileo’s views and conclusions, adducing his own previous speculations, or pointing out, as in the case of Galileo’s idea of earth-light on the moon, the previous conception of[ix] the same explanation of the phenomenon. He rejects, however, Galileo’s explanation of the copper colour of the moon in eclipses. Kepler ends by expressing unbounded enthusiasm at the discovery of Jupiter’s satellites, and the argument it furnishes in support of the Copernican theory.” -Introduction