It seemed
to Galileo as if the planet consisted of three bodies, a large globe
in the centre, and a smaller one on each side. The enigmatical
nature of the discovery led Galileo to announce it in an enigmatical
manner. He published a string of letters which, when duly
transposed, made up a sentence which affirmed that the planet Saturn
was threefold. Of course we now know that this remarkable appearance
of the planet was due to the two projecting portions of the ring.
With the feeble power of Galileo's telescope, these seemed merely
like small globes or appendages to the large central body.
The last Of Galileo's great astronomical discoveries related to the
libration of the moon. I think that the detection of this phenomenon
shows his acuteness of observation more remarkably than does any one
of his other achievements with the telescope. It is well known that
the moon constantly keeps the same face turned towards the earth.
When, however, careful measurements have been made with regard to the
spots and marks on the lunar surface, it is found that there is a
slight periodic variation which permits us to see now a little to the
east or to the west, now a little to the north or to the south of
the average lunar disc.
But the circumstances which make the career of Galileo so especially
interesting from the biographer's point of view, are hardly so much
the triumphs that he won as the sufferings that he endured.
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