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before the other astronomer could look for the planet; Piazzi himself had fallen ill, and the planet, seizing the opportunity (almost like an actual thief with the crowd after him), dodged into the Sun and was lost to view. Perhaps you will not understand rightly what I mean by dodging into the Sun. You know how the Sun goes the round of the Zodiac: The Ram, the Bull, the Heavenly Twins, and so on (have you learnt that verse thoroughly?). As it visits them, each in turn disappears from view in the glare of daylight so that you cannot see the Ram in April, or the Bull in May. Indeed, not only one, but two or three of them are invisible at any given time of year. Now a planet moves about among the constellations: sometimes it is in one that is visible and sometimes in one that is lost in the Sun's glare; and Ceres, as the first-discovered minor planet was called, passed from one to the other very soon after the discovery. It seemed as though she had been found only to be lost again. You may say, could they, not wait till she came out and catch her again? Yes, but sometimes it is very hard to tell when and where a burglar will come out if once you let him disappear. He may get on to the roof and crawl along to other houses, down through them and out at some back door, when the police are watching all the time in the wrong place. A planet is not quite so clever and erratic as a burglar; indeed, if we have watched his or her movements long enough, we can calculate almost exactly where he or she will be at a future time. That is what Kepler and Newton have done for us by finding out the great Law of Gravity which controls the movements. But everything