Forty-three thirteen-year-olds and their homeroom teacher looked up at the stars.
The winter’s constellations, Taurus, Orion, and Canis Major, were already below the western horizon, and the summer’s, Lyra, Hercules, and Libra, had been up for a while. Each star was like a distant eye blinking at the human world from the depths of the universe. But on this night, the cosmic gaze was somewhat different.
On this night, history as known to humanity came to an end.
1
THE DEAD STAR
THE END
In the space within a ten-light-year radius of Earth, astronomers discovered eleven stars: the triple-star system formed from Proxima Centauri, Alpha Centauri A, and Alpha Centauri B; two binary-star systems, Sirius A and Sirius B, and Luyten 726-8 A and Luyten 726-8 B; and four single stars, Barnard’s Star, Wolf 359, Lalande 21185, and Ross 154. Astronomers have not ruled out the possibility that other stars, either especially dim or obscured by interstellar dust, are waiting to be detected.[1]
Astronomers had noticed in this area the presence of a large amount of cosmic dust, like a dark cloud floating in the black night of space. When UV sensors on a satellite were trained on this distant cloud, a peak of 216 mm was found on the absorption spectrum, suggesting that the cloud was likely formed from carbon microparticles; the cloud’s reflectivity suggested that these particles were covered in a thin layer of ice. The particles were in the 2–200 nm range, roughly the same as the wavelength of visible light, rendering it opaque.
It was this cloud that blocked a star eight light-years from Earth. Twenty-three times the diameter of the sun and sixty-seven times its mass, the star was no longer main sequence but was in the final phase of its long evolution, its waning years. We’ll call it the Dead Star.
Even if it had a memory, the Dead Star would not remember its childhood. It was born five hundred million years ago out of a mother nebula. Atomic motion and radiation from the galactic center disrupted the stillness of the nebula, whose particles congealed around a center under gravitational attraction. This stately dust storm endured for two million years, while in its center, hydrogen atoms began to fuse into helium. The Dead Star was born out of this atomic furnace.
After a dramatic childhood and rocky adolescence, fusion energy arrested the collapse of the stellar crust, and the Dead Star entered a lengthy middle age, an evolution that took place over hundreds of millions of years instead of the hours, minutes, and seconds of its childhood, bringing a new point of calm light to the galaxy’s vast starry ocean. But a flyby of the Dead Star’s surface would have revealed that this calm was illusory. It was an ocean of atomic fire, enormous waves of searing flames that churned red and flung high-energy particles out into space like a storm swell. Tremendous energy erupted from the star’s depths and surged in blinding waves in that sea, over which an endless nuclear storm of constant hurricanes raged, and dark red plasma undulated under a strong magnetic field in million-kilometer tornadoes reaching into space like the tendrils of a red tide…. No human mind could grasp the sheer size of the Dead Star; against that sea of fire, Earth was like a basketball tossed into the Pacific Ocean.
The Dead Star ought to have been bright in the visible sky. With an apparent magnitude of −7.5, if not for the interstellar dust incubating another star that sat three light-years distant and blocked its light from reaching Earth, it would have shone on human history with a light more than five times brighter than Sirius, the brightest star in the heavens, bright enough to cast shadows on a moonless night, a dreamy blue adding a dose of sentimentality to human history.
The Dead Star burned a glorious existence without incident for 460 million years, but the cold hand of the law of conservation of energy made certain internal changes unavoidable: the fusion fire depleted hydrogen, and the helium by-product sank to the star’s center and accumulated over time. This change was an exceedingly slow process for such a giant object, one for whom the whole span of human history was the snap of a finger, but after 480 million years, the depletion had a tangible effect: enough of the more inert helium had accumulated that the source of the star’s energy waned. It had grown old.
But other, more complicated physical laws determined that the Dead Star would end its life in a blaze of glory. The density of the helium at its center increased, and the fusion that continued in the surrounding hydrogen produced temperatures high enough to initiate fusion in the helium, consuming nearly all of it at once in a nuclear inferno. The helium fusion caused the Dead Star to shine with a powerful light, but since its energy was only a tenth of that of hydrogen, the effort only further weakened the star. Termed a helium flash by astronomers, the phenomenon’s light reached the patch of interstellar dust three years later, where the relatively long-wavelength red light penetrated the cosmic barrier. That light traveled for another five years before arriving at a far smaller, ordinary star, the Sun, as well as the handful of cosmic dust attracted by its gravitational pull, known to humans as Pluto, Neptune, Uranus, Saturn, Jupiter, Mars, Venus, Mercury, and of course Earth. This took place in 1775.
That evening, in Earth’s northern hemisphere, in the English spa town of Bath, outside a high-end music hall, a German-born organist by the name of Frederick William Herschel was gazing hungrily into the universe through a telescope of his own design. The glittering Milky Way so called to him that he poured his entire life into telescopes, to the extent that his sister Caroline had to spoon him his meals while he continued observations. During the lifetime the most distinguished of eighteenth-century astronomers spent in front of the lens, he marked seventy thousand stars on the map, but he overlooked the one that became most significant to humanity. That night a red body suddenly appeared in the western sky in the constellation Auriga, at the midpoint between Capella and Beta Aurigae. An apparent magnitude 4.5, it wasn’t bright enough for a casual observer to pick out even if they knew its location, but to an astronomer, the red star was nothing less than an enormous lantern that Herschel might have discovered, were he viewing the heavens with the naked eye like pre-Galilean astronomers rather than being glued to the lens. And that discovery might have altered the course of human history some two centuries later. But his attention was entirely commanded by that telescope, just two inches in diameter, pointed in an entirely different direction, as, unfortunately, were telescopes at the observatories in Greenwich and Hven, and everywhere else in the world, for that matter….
The red star in Auriga shone for the whole night, but the next night it had disappeared.
That same night in that same year, on the continent called North America, eight hundred British soldiers crept along a road to the west of Boston, their red uniforms giving them the look of a line of ghosts in the night. Clutching muskets in the chilly spring wind, they hoped to reach the town of Concord, twenty-seven kilometers from Boston, before daybreak, and were under orders from the Massachusetts governor Thomas Gage to wipe out the minutemen’s arsenal and arrest their leadership. But when the sky turned gray and the woods, huts, and pasture fences took shape as silhouettes against the growing light, the soldiers looked about them and found they had only gotten as far as the town of Lexington. From a thicket ahead of them came a sudden flash, and an earsplitting crack broke the stillness of the North American dawn, closely followed by the whoosh of bullets: the quickening in the womb of the embryonic United States of America.
1
Stars discovered after this book’s original date of publication include the dwarf stars Luhman 16A and Luhman 16B (announced in 2013), and sub-dwarf WISE 0855−0714 (in 2014).