Introduction
Adams, John Couch (1819–1892) British Astronomer, Mathematician John Couch Adams, a brilliant scientist often described as shy, reserved, and even self-effacing, is best known as a central figure in a scientific fiasco that sparked an international debate, pit- ted nations against one another, and brought the world of astronomy out of academia and into the life of the average citizen. Adams’s involvement in the missed discovery, and subsequent codis- covery, of the planet Neptune became one of the most important events in the history of astron- omy, from both a scientific and a political point of view.
Early Life and Childhood
Born in 1819, the son of a farmer, Adams reportedly showed great mathematical ability from the time he was young, and at the age of 16 calculated the time of an upcoming solar eclipse. Four years later, in October 1839.
Adams became a student at St. John’s College in Cambridge, a town that Adams stayed tied to for the rest of his life. Shortly after the discovery of Uranus by SIR WILLIAM HERSCHEL, astronomers discovered a baffling problem with that planet’s orbit.
Adams, in his second year of college, suspected that the problem was another planet, writing in 1841 that “the irregularities of the motion of Uranus” had him questioning “whether they may be at- tributed to the action of an undiscovered planet beyond it.”
His studies, and later his work, kept Adams busy, but he planned on “investigating, as soon as possible after taking my degree” (an- other two years away), the possible explanation for the planet’s orbit, believing that he would then “if possible . . . determine the elements of its orbit, etc. approximately, which would prob- ably lead to its discovery.”
Unfortunately, life got in the way, protocol got in the way, and ineffective tools and people got in the way.
The chain of events that took place between Adams’s documented idea in July 1841, in which he suspected the existence of an- other planet, to his computations of the planet’s location, to the actual discovery of the planet in September 1846, was a slow and painful pro- gression.
The time span of more than 5 years al- lowed plenty of time for outside forces and peo- ple to complicate matters, and the result was a full-blown scandal.
The idea that “he who pub- lishes first gets the credit,” which was the pro- tocol of the time, did not help Adams either.
The professional positions and personal obliga- tions of the people involved further complicated the events that followed.
Adams' Education
In 1841 Adams was a second-year student convinced that there was another planet beyond
Uranus. He was overworked with his studies, but still reportedly spent hours by candlelight, work- ing through the night on mathematical compu- tations to pinpoint the planet’s location.
While this was unknown to the rest of the world at the time, Adams was the first person to use Newton’s theory of gravitation as a basis for calculating the position of a planet.
Two years later, in 1843, Adams graduated with extraordinarily high marks from Cambridge, receiving the award of First Smith’s Prizeman and a fellowship at Pembroke College.
He soon became a curator of the Cambridge Observatory, and his career was underway.
In October he completed computations for the location of the planet, and shared his theory with the Astronomer Royal, Sir George Airy. But Airy disagreed, and thought that the problems with the orbit were related to the inverse square law of gravitation, in which gravitation begins to break down over large distances.
Airy’s dismissal of the computations, compounded by new teach- ing responsibilities, kept Adams from pursuing his theory. Despite the setbacks, Adams had a brilliant mind, and although he was not what anyone would ever call aggressive, he was persistent about calculating the planet’s position.
Adams requested additional data on Uranus from Greenwich. Through the director of the Cambridge Observ- atory, Professor James Challis, Adams requested additional data from Airy in Greenwich, and in February 1844, the information was sent. DOMINIQUE-FRANÇOIS-JEAN ARAGO, the director of the Paris Observatory, was also in- terested in Uranus’s orbital problems, and he also thought another planet might be in- volved. In June 1845 he requested that one of his astronomers, URBAIN-JEAN-JOSEPH LE VERRIER, work on the solution to find this planet. Arago did not know about Adams’s work, and Airy did not know that Arago was looking for a planet.
By September Adams’s calculations were complete, and included the location of the planet, its mass, and its orbit. Adams personally took his findings to show Airy, but Airy was away in France, so Adams left a letter of intro- duction written on his behalf by Challis.
Despite the fact that it was common for people from all walks of life to write to and drop in on the Astronomer Royal, Adams’s behavior of showing up without an appointment is often highly criticized and cited as a contributing factor to the fiasco. The following month, Airy wrote to Challis saying that he would see Adams, and Adams traveled once again without an appointment to
see the astronomer. When he arrived, Mrs. Airy told Adams that her husband was out, so he left his card saying that he would return later in the day. She forgot to give the card to Airy, and when Adams returned as promised in the afternoon, he was told that the family was having dinner, which they did every afternoon at 3:30, and he was turned away again.
Adams left his papers for Airy to review, and returned to Cambridge. Airy still questioned Adams’s theory, even after looking at his calculations and explana- tions, and later wrote to him asking specifically whether the new planet could explain some of the discrepancies of Uranus’s orbit.
Many think that Adams was bothered by the question be- cause he thought it was missing the point—he had identified a planet and gave complete and thorough calculations. For whatever reason, Adams did not write back.
Adams Inventions and discoveries
In November 1845 LeVerrier published a pa- per stating that Jupiter and Saturn definitely did not cause Uranus’s orbit, insisting that another factor had to be involved.
On June 1, 1846, he published another paper, this time stating with certainty that another planet beyond Uranus was the only possible explanation for Uranus’s orbit. Airy got a copy of LeVerrier’s paper on June 23, and wrote to him asking the same ques- tion he had asked Adams approximately six months earlier.
This put Airy in the possession of information making him the only one who knew that Adams and LeVerrier were working on the same prediction, and that they in fact came to the same conclusion. Airy told neither of them about the other’s work.
On June 29 Airy received LeVerrier’s reply. With this information, he met with Challis and another astronomer, SIR JOHN FREDERICK WILLIAM HERSCHEL (son of Sir William Herschel, discoverer of Uranus) to dis- cuss the “extreme probability of now discover- ing a new planet in a very short time . . .” “It was so novel a thing to undertake ob- servations in reliance upon merely theoretical deductions; and that while much labour was certain, success appeared very doubtful,” wrote Challis, but on July 29, he started the search by recording stars in the area, which he would have to observe and reobserve over several different evenings, to compare locations and see if one had moved.
Since Challis did not have a cur- rent star map at the observatory, he could not make quick comparisons. He made his second observation on July 30, his third on August 4, and his final observation on August 12, then started comparing his data. Unfortunately, he only looked at the first 39 stars he recorded on August 12 when he made the comparisons to the July 29 data. It was the 49th “star” that later proved to be the planet, but Challis stopped his comparisons before finding this result.
In late August 1846 Hershel, who believed in the existence of the planet, suggested to a friend with a telescope that they could probably see the planet just by looking for it in the sug- gested location. His friend, William Dawes, de- cided that the telescope he owned was not ade- quate enough, and searching for it would be a waste of time. As it turned out, LeVerrier had the same idea.
On August 31 he published a paper with the planet’s orbit, mass, and angular diameter, and suggested that using the data, they could look at the stars in this location, find the one that was a disc rather than a point of light (plan- ets are disc-shaped in a telescope), and quickly find the planet. On September 2 Adams sent Airy new com- putations with a more precise location of the planet. Meanwhile, Dawes wrote to a friend, William Lassell, asking if he would use his larger telescope to help look for it.
But Lassell had a badly sprained ankle and could not get around, so he gave the letter to his maid for safekeeping while he recovered. She promptly lost the let- ter, so Lassell never looked. On September 10 Herschel gave a speech at a British Association event, in which he discussed his belief in the new planet, and at
which Adams was scheduled to present a paper on his findings. As if things could not become a more dreadful comedy of errors, it turns out that there was some confusion as to the sched- uled date of the presentation, and Adams arrived at the session the day after it closed. LeVerrier’s experience in getting the French government to search for the planet soon be- gan to resemble Adams’s experience with the British government: Interest was lacking.
So, on September 18 he wrote to the astronomer JOHANN GOTTFRIED GALLE at the Berlin Academy, giving him the calculations and asking him to search with his telescope. Galle and his assistant, Heinrich d’Arrest, received LeVerrier’s letter on September 23, and since they had a telescope and new star maps success seemed likely. Within the hour, the planet was found. Galle immediately wrote to LeVerrier, “Monsieur, the planet of which you indicated the position really exists.” Back in England, Challis finally received a copy of LeVerrier’s August 31 paper, and he did some more observations. This time he actually saw that one of the stars was a disc, but he pre- ferred to confirm that it was really a planet by observing and comparing movement, which would take time, so he did nothing.
To the surprise of everyone involved, on October 1 London’s prestigious newspaper The Times announced Galle’s sighting of “LeVerrier’s planet.” Challis immediately looked through his telescope again and confirmed that the disc he saw on July 29 had moved. By October 3 the scandal had begun. Herschel informed the public that Adams had made the same prediction earlier than LeVerrier.
The humble Adams was called upon to confirm the time and nature of his computa- tions, and Airy and Challis had to explain them- selves to the press and the public in light of Adams’s virtually ignored, yet significant, work.
Naturally, the British government wanted the credit for the finding, and so it claimed that since they were the first to know about the planet, it was a British discovery. The French government, absent in helping LeVerrier look for the planet, suddenly decided it was time to take action, so it claimed ownership of the dis- covery. And the Germans, who were the first to actually see the planet, received no credit at all. Additional investigations revealed that “LeVerrier’s planet” had been observed and cat- alogued by other, earlier astronomers, including Galileo Galilei on December 28, 1612, and January 27 and 28, 1613, who observed that it had traveled but did not pursue it as a planetary discovery.
The French astronomer Joseph- Jérôme Le Français de Lalande recorded it as a star on May 8 and 10, 1795, as did Herschel on July 14, 1830, and the Scottish-German as- tronomer Johann von Lamont on October 25, 1845, and September 7 and 11, 1846. To add to the debate, American scientists attacked both Adams and LeVerrier, saying that their calculations of the planet’s orbit were so far off (which they were) that its dis- covery was purely a coincidence. None of this seemed to really affect the mild-mannered Adams, who simply did not get embroiled in any of it.
In 1847 John Herschel invited both Adams and LeVerrier to meet with him at his home in Kent. Despite the insistence by the British gov- ernment that Adams had discovered the planet, Adams himself apparently never made that claim, and it is considered common knowledge that he was never bitter about any of it.
He was, instead, a great admirer of LeVerrier’s, and upon meeting at Herschel’s, the two apparently be- came good friends. Adams survived the great fiasco, and both he and LeVerrier became recognized as the codiscoverers of the new planet, named Neptune. Adams went on to participate in other signifi- cant astronomical work, including computa- tions on the acceleration of the Moon, and the
relationship of the Leonids (meteors that origi- nate from a region in the “head” of the constel- lation Leo) with a comet.
In 1848 Adams received the coveted Copley Medal from the Royal Society of London, and in 1859 he became the Lowndean Professor of Astronomy and Geometry at Cambridge University. He stayed in this position for the next 32 years. In 1861 he succeeded Challis as the director of the Cambridge Observatory, and later served two terms as president of the Royal Astronomical Society. Adams passed up two very deserved opportunities for fame. He de- clined Airy’s job as Astronomer Royal when Airy retired, and he refused a knighthood offered by Queen Victoria because he apparently could not afford to keep up the standard of living of a knight. Adams married Eliza Bruce (descendant of Scottish king Robert Bruce) in 1863. He retired from Cambridge in 1891 and died in 1892.
In 1895 a memorial was placed in Westminster Abbey near the memorial to Newton, and many believe that Adams was the greatest English as- tronomer and mathematician since SIR ISAAC NEWTON.
Adam’s memoir, which included the story of his predictions, was published at some point during his life, under the title An explana- tion of the observed irregularities in the motion of Uranus, on the hypothesis of disturbances caused by a more distant planet; with a determination of the mass, orbit, and position of the disturbing body. A crater is named in honor of Adams on the sur- face of the Moon.
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