Within a year, Galileo had built his own telescope and discovered the moons of Jupiter, one of the observations that validated the Copernican theory.
(Galileo; had built; his own telescope; T:Within a year) (Galileo; discovered; the moons of Jupiter; T:Within a year) (the observations; validated; the Copernican theory)
Galileo Galileo the observations
had built discovered validated
his own telescope T:Within a year
the moons of Jupiter T:Within a year
the Copernican theory