Mercury, dist.-- 4 4 + 0 = 4
Venus " 7 4 + 3 = 7
Earth " 10 4 + 6 = 10
Mars " 15 4 + 12 = 16
-- 4 + 24 = 28
Jupiter dist. 52 4 + 48 = 52
Saturn " 95 4 + 96 = 100
(Uranus) " 192 4 + 192 = 196
-- 4 + 384 = 388

All the five planets, and the earth, fitted this rule, except that
there was a blank between Mars and Jupiter. When Uranus was
discovered, also fitting the rule, the conclusion was irresistible
that there is probably a planet between Mars and Jupiter. An
association of twenty-four astronomers was now formed in Germany to
search for the planet. Almost immediately afterwards the planet was
discovered, not by any member of the association, but by Piazzi, when
engaged upon his great catalogue of stars. On January 1st, 1801, he
observed a star which had changed its place the next night. Its motion
was retrograde till January 11th, direct after the 13th. Piazzi fell
ill before he had enough observations for computing the orbit with
certainty, and the planet disappeared in the sun's rays. Gauss
published an approximate ephemeris of probable positions when the
planet should emerge from the sun's light. There was an exciting hunt,
and on December 31st (the day before its birthday) De Zach captured
the truant, and Piazzi christened it Ceres.


The mean distance from the sun was found to be 2.767, agreeing with
the 2.8 given by Bode's law. Its orbit was found to be inclined over