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In 1666 the sleepy little hamlet near Grantham in Lincolnshire, eastern England, hosted a world-changing event centering around one remarkable person. History tells us that this was by no means an “ordinary” person – although in many respects he was just as fallible and human as any other mortal. It’s a measure of the indelible impact that this person had on the world that his name is not only remembered in history lessons but lives on in the fields of mathematics, physics, astronomy, and optics to a greater extent even than that of Galileo. That extraordinary human being was Isaac Newton.

Our story’s central figure, the Italian physicist Galileo Galilei (1564–1642), was intellectually active during the late Renaissance, an exciting and unprecedented period in history. Discoveries in the New World were opening eyes to the idea that our own planet was far vaster and more diverse than anyone had previously dared to suspect. Not only were new discoveries easily disseminated to the educated masses by the printing press, but new ways of thinking about the world were promulgated through pamphlets and books, often couched in the medium of fictional literature.

Galileo’s small telescope showed that the Milky Way was composed of a multitude of stars that were too faint to be resolved individually with the unaided eye. Unlike the planets, which when magnified through a telescope displayed a small but distinct disk, the stars remained as point-like objects. This, along with the fact that the stars displayed no discernable parallax through the instruments in use in the seventeenth century, suggested that the stars were at a truly unimaginable distance from the Solar System. French philosopher Blaise Pascal (1623–1662) conveys a vivid sense of the human reaction to this new-found scale of the Universe when in his Pensees (Thoughts, 1670) he writes of a man without God: “engulfed in the infinite immensity of spaces of which I am ignorant and which know me not… The eternal silence of these infinite spaces frightens me.”

During the three centuries following Galileo, most astronomy was carried out with keen eyes glued to the telescope eyepiece, and records of the Sun, Moon, planets, and objects further out in the Universe were made in the form of written notes or observational sketches. Our knowledge of the Universe was improved through the observations of both amateur and professional astronomers, the distinction between which was often more than a little blurred in centuries past. Advances in telescope optics, including the invention of objective lenses that eliminated much of the false color produced by refracting telescopes, inventions of new forms of optical systems, along with engineering improvements, allowed for bigger and better instruments with which to probe the Universe.