Nice play on words there! I had forgotten who the author was, but your little hint clued me right in.
According to Wikipedia the book was published in 1726, 51 years prior to the ‘discovery’ of the moons.
The moons were described in some detail 51 years prior to their discovery.
There still are some real mysteries left to solve, aren’t there?
That should be 151 years, not 51 years.