He now only thinks of making discoveries in the heavens; but his instrument is too small.  He makes another and larger telescope, which magnifies eight times, and then another which magnifies thirty times; and points it to the moon.  And how indescribable his satisfaction, for he sees what no mortal had ever before seen,—­ranges of mountains, deep hollows, and various inequalities!  These discoveries, it would seem, are not favorably received by the Aristotelians; however, he continues his labors, and points his telescope to the planets and fixed stars,—­but the magnitude of the latter remain the same, while the planets appear with disks like the moon.  Then he directs his observations to the Pleiades, and counts forty stars in the cluster, when only six were visible to the naked eye; in the Milky Way he descries crowds of minute stars.

Having now reached the limit of discovery with his present instrument, he makes another of still greater power, and points it to the planet Jupiter.  On the 7th of January, 1610, he observes three little stars near the body of the planet, all in a straight line and parallel to the ecliptic, two on the east and one on the west of Jupiter.  On the next observation he finds that they have changed places, and are all on the west of Jupiter; and the next time he observes them they have changed again.  He also discovers that there are four of these little stars revolving round the planet.  What is the explanation of this singular phenomenon?  They cannot be fixed stars, or planets; they must then be moons.  Jupiter is attended with satellites like the earth, but has four instead of one!  The importance of this last discovery was of supreme value, for it confirmed the heliocentric theory.  Old Kepler is filled with agitations of joy; all the friends of Galileo extol his genius; his fame spreads far and near; he is regarded as the ablest scientific man in Europe.

His enemies are now dismayed and perplexed.  The principal professor of philosophy at Padua would not even look through the wonderful instrument.  Sissi of Florence ridicules the discovery.  “As,” said he, “there are only seven apertures of the head,—­two eyes, two ears, two nostrils, and one mouth,—­and as there are only seven days in the week and seven metals, how can there be seven planets?”

But science, discarded by the schools, fortunately finds a refuge among princes.  Cosimo de’ Medici prefers the testimony of his senses to the voice of authority.  He observes the new satellites with Galileo at Pisa, makes him a present of one thousand florins, and gives him a mere nominal office,—­that of lecturing occasionally to princes, on a salary of one thousand florins for life.  He is now the chosen companion of the great, and the admiration of Italy.  He has rendered an immense service to astronomy.  “His discovery of the satellites of Jupiter,” says Herschel, “gave the holding turn to the opinion of mankind respecting the Copernican system, and pointed out a connection between speculative astronomy and practical utility.”