Jupiter plus the even greater distance out to Saturn-that the spacecraft did not reach Saturn till September 1979. During the Thousand- Yard walk is the dramatic time to tell people about this, and let them reflect on the refinement with which the spacecraft had to be aimed around the south pole of Jupiter in just such a way that it might five years later drop between Saturn (this acorn) and its rings. Schematic pictures often show the planets on parade at about equal distances- much as when you first arrayed them on the table. This, as we have seen is unrealistic: the intervals are very unequal. There are these features to point out: In general, the intervals get strikingly larger as we go outward. But they increase very irregularly. No need to dwell on this unless someone asks, but for instance the first three jumps actually get smaller; after that they increase, but neither in an arithmetical progression (like 1, 2, 3, 4...) nor in a geometrical progression (like 2, 3, 8, 16...). A more complicated regularity has been discerned; it is known as "Bode's law," but is only a rough rule rather than a law. If Mercury is 4 units of distance from the Sun, the Venus is 4+3, the Earth 4+6, Mars 4+12. Then Jupiter is 4+48 and Saturn more roughly 4+96. The most obvious exception to this "law" is the gap between Mars and Jupiter. This was where your class swooned, on hearing that the next distance