In German Philosophy: A Dialogue, Alain Badiou says
I like Hegel, really. I like him even in all those moments of madness that you mention. He even tried to deduce the exact number of planets as an attribute of the absolute. That was a big risk, which was immediately rewarded by the discovery of an extra planet. Normally, you would expect that to cause the collapse of the whole system, because there are no purely local parts in the Hegelian system; there is a general interlinking of these parts, and if Hegel was wrong about the number of planets, he was perhaps wrong about many other things, too.
I have read what at the time seemed a fair chunk of Hegel. Still, what I read must be well under ten percent of his output, and the deduction of the number of planets will have been somewhere in that other ninety-plus percent. But Hegel must have gone to his grave believing that there were seven planets, for Uranus was discovered a few years after his death.
Badiou's remark interested me also because of a curious passage in W.V.O. Quine's essay "Reference and Modality" (collected in From a Logical Point of View), where "According to the strict sense of 'necessarily' and 'probably'"
9 is necessarily greater than 7
is among the statements counting as true, and
The number of planets is necessarily greater than 7
among those counting as false. Quine introduces 7, 9, and the number of planets into Word and Object also. Did he have Hegel's argument in mind?