Galileo with his home built telescope had by then discovered the moons of Jupiter and reasoned, that they could be used to determine 'longitude'.
(they; to determine; longitude) (Galileo; had; ) (Galileo; reasoned; ) Context(Galileo reasoned,List([0, 94))):(they; could be used; to determine 'longitude)
Galileo reasoned,List([0, 94))
they Galileo Galileo they
to determine had reasoned could be used
longitude
to determine 'longitude