The Pluto Files: The Rise and Fall of America's Favorite Planet Read Online Free
Author: Neil deGrasse Tyson
known comets. At this point, you would have had to be both blind and boneheaded to resist calling the new object a planet.
But all was not orderly in the solar system. Uranus was behaving badly. This new planet’s trajectory around the Sun was not following the path Newton’s law of gravity would have it take after all known sources of gravity were accounted for. Some astronomers suggested that Newton’s laws might be invalid at such large distances from the Sun. Not so crazy: under new or extreme conditions, the behavior of matter can, and occasionally does, deviate from the predictions of the known laws of physics. Only if Newton’s theory of gravity had been nascent and untested would one have good reason to question it. By the time Herschel had discovered Uranus, Newton’s laws were on a 100-year run of successful predictions. Most famous among them was Edmond Halley’s predicted return in 1759 of the comet that would be named in his honor.
The simplest conclusion? Something was lurking undiscovered in the outer solar system—something whose gravity was unaccounted for in the expected orbital path of Uranus.
Beginning in the late eighteenth century, the French mathematician Pierre-Simon de Laplace developed perturbation theory, which he published in his influential multivolume treatise Mécanique Céleste . Laplace’s new math gave astronomers an indispensable tool to analyze the small gravitational effects of an otherwise undetected celestial object. Mathematicians and astronomers across Europe, armed with these new tools of analysis, continued to investigate what might be perturbing Uranus. In 1845, a young, unknown English mathematician, John Couch Adams, approached Sir George Airy, Britain’s astronomer royal, with a request that he search the sky for an eighth planet. But neither looking for planets nor following the leads of young, spunky mathematicians were part of the astronomer royal’s job description, so Adams’s request was dismissed. The next year, the French astronomer Urbain-Jean-Joseph Leverrier independently derived similar calculations. On September 23, 1846, he communicated his prediction to Johann Gottfried Galle, who was then assistant director of the Berlin Observatory. Searching the sky that same night, Galle found the new planet, soon to be named Neptune, within a single degree of the spot Leverrier had predicted.
But once again, all was not orderly in the solar system. Uranus was still behaving badly, although less so now that the gravity from Neptune had been accounted for. Meanwhile, Neptune’s orbit had some peculiarities of its own. Could yet another planet be awaiting discovery?
Figure 2.1. An 1895 portrait of Percival Lowell looking dapper. Lowell, the founder of Arizona’s Lowell Observatory, launched the search for Planet X, which led to the discovery of Pluto.
In his early years, Percival Lowell indulged a fanatical, even delusional fascination with Mars, claiming that intelligent civilizations were in residence there, digging networks of canals to channel water from the polar ice caps to the cities. He imagined a diminishing water supply, leaving them on the brink of extinction, which fed the War of the Worlds , Martian invasion fever of the day. But he devoted most of the rest of his life to the search for the object he called Planet X (X for the algebraic unknown)—the mysterious body in the outer solar system that continued to perturb Neptune. By this reckoning, of course, one might have previously identified Neptune as the Planet X to Uranus
All efforts to predict the location of Planet X based on perturbations to Neptune came up empty. Any discovery would require a large-area survey of the sky.
When looking for a planet, nobody wants to pore over images of the sky that contain countless millions of dots, hoping to spot the one that moved between one photo and the next. Fortunately, an ingenious mechanical-optical device known as a blink comparator would come to
But all was not orderly in the solar system. Uranus was behaving badly. This new planet’s trajectory around the Sun was not following the path Newton’s law of gravity would have it take after all known sources of gravity were accounted for. Some astronomers suggested that Newton’s laws might be invalid at such large distances from the Sun. Not so crazy: under new or extreme conditions, the behavior of matter can, and occasionally does, deviate from the predictions of the known laws of physics. Only if Newton’s theory of gravity had been nascent and untested would one have good reason to question it. By the time Herschel had discovered Uranus, Newton’s laws were on a 100-year run of successful predictions. Most famous among them was Edmond Halley’s predicted return in 1759 of the comet that would be named in his honor.
The simplest conclusion? Something was lurking undiscovered in the outer solar system—something whose gravity was unaccounted for in the expected orbital path of Uranus.
Beginning in the late eighteenth century, the French mathematician Pierre-Simon de Laplace developed perturbation theory, which he published in his influential multivolume treatise Mécanique Céleste . Laplace’s new math gave astronomers an indispensable tool to analyze the small gravitational effects of an otherwise undetected celestial object. Mathematicians and astronomers across Europe, armed with these new tools of analysis, continued to investigate what might be perturbing Uranus. In 1845, a young, unknown English mathematician, John Couch Adams, approached Sir George Airy, Britain’s astronomer royal, with a request that he search the sky for an eighth planet. But neither looking for planets nor following the leads of young, spunky mathematicians were part of the astronomer royal’s job description, so Adams’s request was dismissed. The next year, the French astronomer Urbain-Jean-Joseph Leverrier independently derived similar calculations. On September 23, 1846, he communicated his prediction to Johann Gottfried Galle, who was then assistant director of the Berlin Observatory. Searching the sky that same night, Galle found the new planet, soon to be named Neptune, within a single degree of the spot Leverrier had predicted.
But once again, all was not orderly in the solar system. Uranus was still behaving badly, although less so now that the gravity from Neptune had been accounted for. Meanwhile, Neptune’s orbit had some peculiarities of its own. Could yet another planet be awaiting discovery?
Figure 2.1. An 1895 portrait of Percival Lowell looking dapper. Lowell, the founder of Arizona’s Lowell Observatory, launched the search for Planet X, which led to the discovery of Pluto.
In his early years, Percival Lowell indulged a fanatical, even delusional fascination with Mars, claiming that intelligent civilizations were in residence there, digging networks of canals to channel water from the polar ice caps to the cities. He imagined a diminishing water supply, leaving them on the brink of extinction, which fed the War of the Worlds , Martian invasion fever of the day. But he devoted most of the rest of his life to the search for the object he called Planet X (X for the algebraic unknown)—the mysterious body in the outer solar system that continued to perturb Neptune. By this reckoning, of course, one might have previously identified Neptune as the Planet X to Uranus
All efforts to predict the location of Planet X based on perturbations to Neptune came up empty. Any discovery would require a large-area survey of the sky.
When looking for a planet, nobody wants to pore over images of the sky that contain countless millions of dots, hoping to spot the one that moved between one photo and the next. Fortunately, an ingenious mechanical-optical device known as a blink comparator would come to
Readers choose
Cathy Yardley
Valmore Daniels
Samantha Winston
Morticia Knight
Josh Berk
Stephanie Janes
Anne Rivers Siddons
E.R. Punshon
Tod Goldberg
A. L. Haskett