covery, in its bearing on the Copernican theory, was that of the moons of Jupiter, in January 1610. As they exhibited motions precisely similar to those which Copernicus had assumed for the whole solar system, they strongly fortified his theory. It was placed beyond all doubt that our planet was not the centre of all the heavenly bodies, since Jupiter's moons revolved round him. The latter was brought, so to speak, by the discovery of his attendants, into relations with the earth which, considering the prevailing views, were humiliating enough, and the more so since Jupiter had four satellites while the earth had only one. There remained, however, the consoling assurance that he and they revolved round our abode!
In honour of the reigning house of his native country, and as an acknowledgment of favours received from it (for since the accession of Cosmo II.[1] Galileo had been in high favour), he called Jupiter's moons "Medicean stars." The urgent solicitude of the French court to gain, by Galileo's aid, a permanent place on the chart of the heavens, is very amusing. Thus, on 20th April, 1610, he received a pressing request, "in case he discovered any other fine star, to call it after the great star of France, Henry IV., then reigning, the most brilliant in the whole universe, and to give it his proper name of Henry rather than that of the family name of Bourbon." Galileo communicated this flattering request, as he seems to have considered it, with much satisfaction to the secretary of the Tuscan court, Vincenzo Giugni, in a letter from Padua, on 25th June, 1610,[2] as an evidence of the great importance attached to his telescopic discoveries. He added that he did not expect to find any more planets, as he had already made many very close observations.
- ↑ Cosmo II. showed all his life a sincere attachment to his old teacher, Galileo. From 1605, before Cosmo was reigning prince, Galileo had regularly given him mathematical lessons during the academical holidays at Florence, and had thereby gained great favour at the court of Tuscany.
- ↑ Op. vi. pp. 107-111.
