Isaac Newton first discovered how gravity keeps satellites in orbit when he observed how the moon orbits the earth.
(Isaac Newton; discovered; how gravity keeps satellites in orbit when he observed how the moon orbits the earth; T:first) Context(Isaac Newton discovered,List([0, 29))):(gravity; keeps; satellites; in orbit; T:when he observed how the moon orbits the earth) (he; observed; how the moon orbits the earth) Context(he observed,List([73, 84))):(the moon; orbits; the earth)
Isaac Newton discovered,List([0, 29)) he observed,List([73, 84))
Isaac Newton gravity he the moon
discovered keeps observed orbits
how gravity keeps satellites in orbit when he observed how the moon orbits the earth T:first
satellites in orbit T:when he observed how the moon orbits the earth
how the moon orbits the earth
the earth