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THE OUTER PLANETS
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well look upon them en bloc, inasmuch as one attribute of the asteroids concerns them generically rather than specifically, and is of great interest both from a mechanical
Orbits of the Outer Planets.
and an historical point of view. For, in fact, it is what led to their discovery. Titius of Wittenburg, about the middle of the eighteenth century, noticed a curious relation between the distances from the Sun of the then known planets. It consisted in a sort of regular progression, but with one significant gap. Bode was so struck by the gap that he peopled it with a supposed
