He focuses on pivotal events, like Galileo's first use of the telescope in 1609 and 1610, when he discovered four moons of Jupiter, and the 1996 observation of 40 billion galaxies by astronomers using the Hubble Space Telescope.
(He; focuses; ) (he; discovered; four moons of Jupiter) (astronomers; using; the Hubble Space Telescope)
He he astronomers
focuses discovered using
four moons of Jupiter
the Hubble Space Telescope