Free The Day We Found the Universe by Marcia Bartusiak

ladder from a rather modest background as a carpenter's son. After serving as a watchmaker's apprentice, seaman, and then teacher of mathematics and navigation, he went on to make a comfortable living in England giving private lessons on architecture and science to noble families. He tutored Lord Cornwallis's daughters (sisters of the Revolutionary War general), hunted with the Earl of Halifax, and dined regularly for a time with the Duke and Duchess of Kent.

    With the backing of his wealthy benefactors, Wright published a lavish book in 1750 titled An Original Theory; or, New Hypothesis of the Universe , which attempted to explain the structure of the Milky Way. Then thirty-nine years old, the Englishman applied his self-taught expertise in surveying and geometry to the question he had been pondering, off and on, for many years: Why does the Milky Way appear as a misty streak that stretches across the celestial sphere? Galileo with his telescope had revealed that this cloudlike band was composed of innumerable stars, but why should the stars arrange themselves in such a streamlike fashion?

    Thomas Wright of Durham
(From Thomas Wright's An Original Theory; or,
New Hypothesis of the Universe, 1750)
    Limited in formal education, Wright filled his book with arcane theological digressions, as was the style of his time, but in the midst of his ramblings he introduced the startling idea, now deemed obvious, that our position in space affects how we perceive our celestial environment. He proposed that the Milky Way could be “no other than a certain Effect arising from the Observer's Situation, I think you must of course grant such a Solution at least rational, if not the Truth; and this is what I propose by my new Theory.” Hedging his bets, he offered a couple of explanations for the Milky Way's appearance. One model pictured the stars moving in a vast ring, much like the rings of Saturn, around a central point. But, strongly guided by his religious views, he preferred to think of the Milky Way as a thin spherical shell of stars—essentially a bubble—with the solar system on the surface and the Eye of Providence, the “agent of creation,” residing in the center.

    Thomas Wright's engraving of the Milky Way,
depicting it as a disk of stars (From Thomas Wright's
An Original Theory; or, New Hypothesis of the Universe, 1750)

    Wright included a number of lush illustrations, thirty-two in all, which conveyed his seminal ideas better than the text itself. One engraving—the one still found in textbooks today—displays the Milky Way as a flat layer of stars. This was a first step in imagining his huge spherical shell. “I don't mean to affirm that [the disk] really is so in Fact,” he wrote, “but only state the Question thus, to help your Imagination to conceive more aptly what I would explain.” Looking along the plane of Wright's big, gently curving shell, in which the Sun is embedded, Earth's inhabitants would readily perceive a disklike structure. The Milky Way appears as a band, mused Wright, because we observe this thin layer of stars edge-on; when looking away from the plane, stargazers see fewer stars.
    Wright went on to consider whether certain cloudy spots, then being observed in the heavens in greater numbers, might be additional creations, bordering upon us but “too remote for even our telescopes to reach,” countless spheres with many “Divine Centres.” He seemed to be echoing the Swedish philosopher Emanuel Swedenborg, who in 1734 also wondered if “there may be innumerable other spheres, and innumerable other heavens similar to those we behold, so many, indeed, and so mighty, that our own may be respectively only a point.”

    If left there, Wright's imaginative ideas and dazzling illustrations would have likely generated hardly a footnote in astronomical history. He even reverted to a more medieval cosmic model, outrageous in its fires-of-hell imagery, some years later. But as British historian