The Planets (16 page)

It was he who urged William to write a paper for the Royal Society, which William titled simply “Account of a Comet.” One of the members of the Society read it aloud at the April meeting in London, while we remained in Bath, for William was still engaged full-time as organ master at the Octagon Chapel, and moreover the inadvertent discovery of the “comet” had interrupted a busy program of stellar observing and measuring separations between double stars. Though we declined to go to
London, soon most of London came to us, to see our little house with its basement workshop and the seven-foot telescope in the garden.
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Shortly after William’s comet aroused our interest, it took a summer holiday, spending several months out of sight in the daytime sky, so that no one could amass the observations required to establish its orbit. When it returned at the end of August, we—and here William and I were joined by I daresay half the astronomers in Europe, not to mention Russia—all fixated upon it. Night after night we strove to fit our observations along a typical comet’s parabolic path, while the object refused to obey our rules, and would move stubbornly in a circular arc. All through the autumn it failed to brighten for us; it denied us the delight of seeing it flash its tail. By November the truth finally dawned: The comet was a planet at twice the distance of Saturn!

As I have taken pains to explain to you, Miss Mitchell, our “Eureka!” moment followed the detection of the body by more than half a year.
William had uncovered one thing that proved to be quite another. When the magnitude of his feat shone clear, and word spread that he had single-handedly doubled the width of the Solar System with this distant planet, King George offered his official protection, including a handsome stipend of about two-thirds Dr. Maskelyne’s salary. The planet could not have arrived at a more propitious moment, given the crown’s recent loss of the Colonies in America.

William, universally hailed as the first man in history to discover a planet, ceased offering music lessons and performing in concerts to become a full-time astronomer. In France some people campaigned to name his new find “Planet Herschel,” just as yours is “Comet Mitchell.” Men who had never before heard of William conceded that his homemade telescopes had put the tools of every great observatory to shame. Not a visitor left our home unshaken by what William had built with his own hands and at his own expense. Hardly a congratulatory letter arrived that did not include a request for William to sell the writer an instrument.

None of the adulation turned William’s head, however, and he would hear none of “Planet
Herschel.” We both felt that while it was all well and good for comets to carry their discoverers’ names—since this practice had precedent in our field, and the number of comets might be legion—the naming of a planet, being such a much rarer occasion, begged for different criteria.

William suggested “Georgium Sidus,” to acknowledge the King’s kindness, though it was quickly pointed out that any reference to national allegiance might be misplaced in a heavenly body. Many other names came forward before the idea of “Uranus” occurred to Herr Bode in Berlin, who sought safety in mythology.
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Bode published an annual ephemeris, which gave him an influential voice in such decisions, but even so, the planet answered to three names—“Uranus” in most of Europe, “Herschel” in France, and “the Georgian” in England—for SIXTY YEARS before “Uranus” gained currency. In that interim, a prodigious chemical experimenter—another German, named Klaproth—extracted a metal from pitchblende and called it “Uranium.” He told us that alchemists of old had always given planet names to
their metals, and he thought the new planet deserved to have one christened in its honor.
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The focus in astronomy remained the establishment of the planet’s orbit, no matter what its name. We also wondered how “Uranus” had escaped prior detection, for although William had sighted it through a superb telescope, other astronomers easily found it with inferior instruments once he told them where to look. This suggested that old records might yield helpful early notes on the planet’s past positions, set down innocently by observers who had mistaken it for a star. Herr Bode, perhaps because of his dedication to his own yearbooks full of tables, took up this task and was soon rewarded for his effort. He found a sky chart from 1756 that included a star no longer to be seen at its given coordinates. That spot now stood empty, while the trail of the planet Uranus, as far as anyone had succeeded in describing it, would have touched that exact point in that very year. This proved a most agreeable vindication, and sent Bode scurrying to find more ancient mentions of our new planet. Indeed, William had hardly been the first to see Uranus for what it
was NOT! The venerable Mr. Flamsteed had listed it in his star catalog of 1690, in the constellation of Taurus the bull.
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This was not as happy a match, however, since no one could make Mr. Flamsteed’s star—now missing—mesh precisely with the path of Uranus as we understood it. Some were tempted to dismiss the information from Greenwich, blaming carelessness or an antiquated telescope for the discrepancy. But I was intimately acquainted with the star catalog of Mr. Flamsteed, a renowned observer in his day and the quintessential Astronomer Royal (perhaps even more perfectionist by nature than his successors), and it seemed unlikely he would have erred in his notations. You can imagine the astronomical dilemma: On the one hand, we desperately needed the old data to aid our calculations, since distant Uranus moved so painfully slowly, and no one relished the thought of spending seventy or eighty years to track its motion once around the Sun! On the other hand, if the ancient observations confounded the best current sense of the orbit’s shape, what help could they provide?

As our new planet continued its strange peregrinations, William built ever larger telescopes. It was through one of these, on a January night in 1787, when our thermometer registered thirteen degrees Fahrenheit, that William discovered Uranus’s two moons. He never proposed proper names for either body, nor for the two satellites he found two years later at Saturn, but my nephew, who was quite the literary scholar before following his father’s footsteps in astronomy (perhaps you are familiar with John’s translation of the
Iliad?
), named them all. The nomenclature for the Saturn system rests squarely on the Greco-Roman myths, but John selected the Uranian lunar names from Shakespeare! As a well read librarian, Miss Mitchell, you of course recognize Oberon and Titania as the king and queen of the fairies from
A Midsummer Night’s Dream,
though I believe the allusion has escaped many another astronomer.

As years passed in watching William’s planet creep about the sky, the deplorable difficulties with its orbit worsened. The more we accumulated new observations, and the more we extracted ancient sightings from observatory files, the less these could be reconciled. It was proving impossible to predict where Uranus would be even a year
or two hence, though most astronomers could assess the future whereabouts of Jupiter or Saturn to within a hair’s breadth till the end of time. Thus the great beauty of the great Newton’s contribution seemed tarnished by the recalcitrant behavior of Uranus.

Things still stood unsettled, sad to say, when William passed away, forty years after the discovery of his planet. I left England at that point, returning to Hanover to live with my brother Dietrich. Neither of us yet realized that William’s life span had equaled the 83.7-year orbital period of Uranus. (Is that not a remarkable coincidence, Miss Mitchell?!) We knew only that the errors in fitting predictions to observations were growing ever more egregious. The last explanation to reach William before he died suggested that a large comet had struck Uranus just prior to its discovery, and the impact had altered the planet’s course. This supposed collision gave probable cause for the rift between the old data and the new, though it seemed almost too imaginative a solution to be believed—more like some device from Shakespeare’s theater, or the Greek tragedy, where gods descend on contraptions to tidy the loose ends of a drama.

Surely some astronomers welcomed the impact idea, but, shortly after William’s death, the orbital predictions based on a comet collision ALSO proved incapable of mapping our planet’s route. There was nothing left for the mathematicians, I suppose, but to insist upon another large planet lurking undiscovered in the deep, beyond Uranus, pulling it off course. How William would have applauded the diligence that discerned such a world in the mind’s eye, before it came to light in the sky, purely by harnessing the intellect to paper and pencil! What would he say to the news of the two now celebrated young gentlemen, who both independently discovered the same new planet, without either one’s ever so much as putting his eye to a telescope, or even knowing which end of it to peer through?
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Only think, Miss Mitchell, of the feats of computation required to build an orbit in the air for a body not known to exist. Think of the bewildering array of possibilities that must first be conjured and then tested one by one to induce this
hypothetical body, on its hypothetical travels, to assume responsibility for all of Uranus’s waywardness. I have heard it said M. Leverrier covered ten thousand sheets of paper with his figuring, and not for a moment do I doubt that estimate. Mr. Adams cannot have done less. And yet, after such immense labor, with each man persevering unaware of the other’s toil, both of them had to BEG the chief astronomers of their respective countries to point telescopes toward the heavenly vicinity where the proposed planet could be found.

That the current Astronomer Royal all but ignored the inexperienced, unpublished Mr. Adams is sad, but not difficult to fathom.
*
M. Leverrier, on the other hand, was already famously distinguished in Parisian scientific associations, and had PUBLISHED his predicted position for the planet, yet he, too, FAILED to gain the cooperation of his national Observatory. (Were you, Miss Mitchell, per chance among the small cadre of independent astronomers who heeded M. Leverrier’s call to
action? I understand that several Americans tried to locate the planet according to his directions.)

The persistent M. Leverrier ultimately succeeded in circumventing official channels via his written request to young Dr. Galle, a SUBORDINATE at the Berlin Observatory. Galle, fresh from his graduate studies, had had the good fortune to observe Comet Halley in 1835, and then the good sense to send his thesis to Leverrier, so that an affinity had developed between them.
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(I bring up these details to urge you, Miss Mitchell, always to announce your findings as soon as you possibly can, not just to garner credit for yourself when credit is due, but because our science thrives on shared information.) Galle surely knew he could lose his post for turning the telescope toward Leverrier’s hunch without permission, and he must have appealed with just the right degree of earnestness and obsequiousness to Prof. Encke. Fortunately for all of them, Encke was hurrying home to his own birthday celebration that evening. Had it not been for his rushing out on
account of the party preparations, he might have denied his permission.

Now picture the scene later that night, when Galle and his assistant arrive, breathless and unannounced, at Encke’s house, to tell him they have actually FOUND Leverrier’s planet!! Meanwhile in England, unbeknownst to all, another pair of astronomers seeks the supposed new planet in a SECRET HUNT, which has at long last been authorized by the Astronomer Royal. And where is the grand personage of the Astronomer Royal the night the new planet makes its entry on the stage of the world? Mr. Airy is here in Germany(!) perhaps only a few miles from the road where Galle rushes through the dark with his extraordinary news! Why, the situation has all the elements of a farce, except that it embodies the finest imaginable testimony to the validity of Newton’s laws.

Following on the heroic mathematics of Adams and Leverrier, and the stunning confluence of their timing, Galle’s espying of the planet through the telescope could be considered almost anti-climactic. I feel certain, however, that it will make his career, and that, whatever else he accomplishes in life, Galle will be known forever as the man who first saw Neptune—or “Oceanus” or “Leverrier,”
as its name may be, though here we are already happy with “Neptune.”

My nephew might well have preceded Galle, and made Uranus and Neptune a pair of father-and-son discoveries(!), for in July of 1830 John’s explorations had taken him to the very neighborhood of the sky—almost to the street and house number, if you will—where Neptune was then residing, though he did not knock at that door. John’s good nature kept him from expressing any personal remorse for his oversight, however, and also helped him quell this past year’s awful national sparring between France and England over claim to the Neptune territory. As my nephew informs me, Mr. Adams had pinpointed the planet at least ten months ahead of M. Leverrier, yet told no one except his superior at Cambridge and the Astronomer Royal at Greenwich. As a result of his cautious silence, Mr. Adams is denied the laurels, and although he graciously accepts second place, his countrymen would rather see him decorated a hero. (And not a few of them would send Mr. Airy to the gallows!)

Yet no rancor, I am told, divides the two key individuals, for Mr. Adams and M. Leverrier
established an immediate rapport when they met last June at Oxford, and grew more friendly during a stay at my nephew’s home in July. I suppose the strength of their common obsession unites them. They are as drawn to each other as their planet and my brother’s planet are bound by the laws of celestial mechanics. For a long time each of these men was ignorant of the other, acting independently of the other, just as Uranus and Neptune seemed unaffected by each other when parted by the vast separations which their orbits allow. But soon after my brother discovered Uranus, his planet neared the environs of Neptune, where the two bodies—one in the limelight, the other behind the scenes—together revealed the full force of their mutual attraction.