Now we come to his most brilliant, at least his most sensational, discovery. Examining Jupiter minutely on January 7, 1610, he noticed three little stars near it, which he noted down as fixing its then position. On the following night Jupiter had moved to the other side of the three stars. This was natural enough, but was it moving the right way? On examination it appeared not. Was it possible the tables were wrong? The next evening was cloudy, and he had to curb his feverish impatience. On the 10th there were only two, and those on the other side. On the 11th two again, but one bigger than the other. On the 12th the three reappeared, and on the 13th there were four. No more appeared. Jupiter, then, had moons like the earth--four of them in fact!--and they revolved round him in periods which were soon determined. The news of the discovery soon spread and excited the greatest interest and astonishment. Many of course refused to believe it. Some there were who, having been shown them, refused to believe their eyes, and asserted that although the telescope acted well enough for terrestrial objects, it was altogether false and illusory when applied to the heavens. Others took the safer ground of refusing to look through the glass. One of these who would not look at the satellites happened to die soon afterward. "I hope," says Galileo, "that he saw them on his way to heaven." The way in which Kepler received the news is characteristic, though by adding four to the supposed number of planets it might have seemed to upset his notions about the five regular solids. He says: "I was sitting idle at home thinking of you, most excellent Galileo, and your letters, when the news was brought me of the discovery of four planets by the help of the double eye-glass. Wachenfels stopped his carriage at my door to tell me, when such a fit of wonder seized me at a report which seemed so very absurd, and I was thrown into such agitation at seeing an old dispute between us decided in this way, that between his joy, my coloring, and the laughter of us both, confounded as we were by such a novelty, we were hardly capable, he of speaking, or I of listening. "On our separating, I immediately fell to thinking how there could be any addition to the number of planets without overturning my _Mysterium Cosmographicon_, published thirteen years ago, according to which Euclid's five regular solids do not allow more than six planets round the sun. But I am so far from disbelieving the existence of the four circumjovial planets that I long for a telescope to anticipate you if possible in discovering two round Mars--as the proportion seems to me to require--six or eight round Saturn, and one each round Mercury and Venus." As an illustration of the opposite school I will take the following extract from Francesco Sizzi, a Florentine astronomer, who argues against the discovery thus: