The demolition of the crystalline heavens took about seventy years and proceeded blow by blow. Copernicus, in 1543, moved the Earth but kept the spheres; his universe is still a nest of circles, only re-centered. The first crack was observational: the new star of 1572 and the comet of 1577, whose parallax Tycho Brahe measured with unprecedented care, both lay above the Moon, in the region where Aristotle's physics permitted no change, and Tycho showed the comet would have to smash through any solid spheres in its path. He concluded, in his own words, that the machinery of the heavens was not a hard and impervious body of orbs but fluid and open. Kepler delivered the structural blow in 1609: planetary orbits are ellipses, not circles, and no rotating sphere can carry an ellipse; the planets swim free, moved by a force from the Sun.
Galileo's telescope added indignities, mountains on the Moon, satellites around Jupiter, spots on the Sun, phases of Venus, each a small refutation of celestial perfection, and Newton in 1687 completed the transfer of explanatory power from geometry to gravitation, one law for apple and Moon alike. What fell with the spheres was more than an astronomy. The cosmos ceased to be a hierarchy with man at the humble center and God past the circumference; it became homogeneous space, the same physics everywhere. Pascal, mid-collapse, recorded the new sensation exactly: the eternal silence of those infinite spaces frightens me. The old model survives where it always lived best, in poetry, liturgy and the imagination of ascent.