A dinosaur looks up as a massive meteor falls through the sky 65 million years ago. DINOSAUR DOOMSDAY The dinosaurs and most other life on the planet were wiped out rapidly in a cataclysm called the Cretaceous-Tertiary Event, which occurred about 65 million years ago. Though the explanation is still conjecture, many scientist believe that an asteroid about 10 kilometers (6.2 miles) across struck the planet near present-day Chicxulub in the Yucatan region, releasing a thermal blast of energy that killed many of the animals and plants on Earth in one fell swoop. The collision also would have spewed enormous amounts of debris into the atmosphere, blocking solar radiation and shutting down the plant-based food chain.
Another Asteroid Armageddon? The current knowledge of that past cataclysm leads many to fear that it might happen again, since NASA has identified more than 9,000 objects whose paths take them in the vicinity of Earth. Asteroids the size of the one that possibly caused the Cretaceous-Tertiary extinction event probably only strike our planet, on average, about once every 100 million years. But however remote, the possibility that such a collision could cause human extinction has led scientists to contemplate methods for changing the path of a potential killer asteroid.
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The Biblical story of Noah's Ark and the Flood is portrayed in a mid-19th century copy of "Grand Catechisme des Familles" (Christian Doctrine for Families). THE GREAT FLOOD Traditional interpretations of the Book of Genesis hold that the Great Flood occurred in 2350 BC.
A Real Great Flood? Other ancient cultures offer strikingly similar accounts of floods that destroyed civilization. Perhaps the best known of those stories, the Mesopotamian "Epic of Gilgamesh," dates back to at least 2100 BC, probably centuries before Genesis was written. Some researchers believe that there may actually have been a massive flood long before any of these stories were written. Around 5600 BC, they suggest, a warming period in the climate caused melting glaciers to send an massive onrush of water cascading from the Mediterranean into the Black Sea area, transforming it into a saltwater lake . One 1997 study suggests that 155,400 square kilometers (60,000 square miles) of land was flooded.
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In this illustration from a 1665 edition of Ovid's "Metamorphoses," men flee from a deadly downpour unleashed upon them by the command of the ancient god Jupiter (Zeus, to the Greeks). JUPITER'S DELUGE According to classical Greek and Roman mythology, humans were fashioned by the titan Prometheus, in the manner that a potter creates figurines from clay, sometime during the reign of Kronos, the titan deity who preceded Jupiter as the master of the universe. When human behavior angered the gods, Jupiter sent the rains to flood the Earth's surface, with the aim of exterminating humanity.
Prometheus' son Deukalion and his wife Pyrrha, however, sailed on a ship above the waves and survived the deluge. Upon landing on the peak of Mount Parnassos, they offered a sacrifice to Jupiter, who then granted their wish that humanity be regenerated.
Many consider the parallels between this story and that of Noah's Flood to be far from coincidental, thus lending more support to the theory that there really was a great flood some time in late prehistory.
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This hand-colored woodcut depicts the destruction of the ancient city of Pompeii by the eruption of Mount Vesuvius in 79 A.D. POMPEII'S FIERY DEATH Just after midday on August 24, 79 A.D., the Mount Vesuvius volcano exploded, shooting a column of smoke 30 kilometers (19 miles) into the sky and burying the city under three meters (nine feet) of volcanic ash, pumice and other debris, trapping terrified residents and causing roofs to fall in. The next morning, there was a second wave of more ash and flows of molten material that piled another three meters atop Pompeii.
It's unclear exactly how many of the city's 10,000 to 20,000 inhabitants were killed, but the death toll probably was extremely high. Researchers have discovered that the 10-kilometer (six mile) area round the city was subjected to surges of heat of between 260 to 593 degrees C (500 and 1100 degrees F), which probably caused most people to die instantly. A neighboring city, Herculaneum, was destroyed by a subsequent wave of the eruption.
The suddenness and totality of the destruction - graphically recorded by ancient historians - has made the death of Pompeii emblematic of man's vulnerability to the untamed forces of nature that have little regard for human civilization.
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In this illustration of a scene from the Biblical Book of Revelation, the Four Horsemen of the Apocalypse ride the Earth to seal the doom of humanity. FOUR HORSEMEN OF THE APOCALYPSE The horsemen appear in Revelation Chapter 6 as the "seven seals" are opened. With the opening of the first seal, the first rider - a bow-wielding, crowned figure on a white horse who is "bent on conquest" - suddenly materializes. In succession, three more seals are opened, and three more horses and riders appear: a sword-brandishing rider on a red horse who symbolizes war, a rider on a black horse who bears scales to symbolize famine, and a fourth on a pale horse whose name is Death. As Revelation 6:8 details, "They were each given power over a fourth of the earth to kill by sword, famine and plague, and by the wild beasts of the earth."
While many scholars interpret Revelation as an allegory for the conflicts between the early Christian church and the power of Rome, Christians who believe in a literal interpretation of the Bible see it as a prophecy of a dark future in which a corrupt humanity will be overwhelmed by a succession of catastrophes.
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This 1961 photomontage shows an atomic mushroom cloud rising in the middle of a crowd of helpless people. NUCLEAR APOCALYPSE Though humans have long feared that an all-powerful deity would become angry and choose to destroy them, the atomic age brought a new fear - that humans had made themselves gods, in a sense, who possessed the power to wipe out their own kind. Physicist J. Robert Oppenheimer, upon witnessing the first detonation of an atomic bomb in New Mexico in July 1945, later remarked that the sight brought to mind a fragment of the Bhagavad Gita, the ancient Indian scripture: "Now, I am become death, the destroyer of worlds." His disturbing vision became more tangible less than a month later, when two atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki, killing 225,000 people and reducing vast sections of both cities to rubble.
The Bomb's Still Here In a radio address afterward, then-President Harry Truman urged the Japanese to surrender before they faced the further wrath of "the force from which the sun draws its power" - a description that, before the development of the hydrogen bomb, technically was inaccurate, but nevertheless chilling. Even more ominously, Truman also noted, as an afterthought, that the U.S. needed to research "possible methods of protecting us and the rest of the world from the danger of sudden destruction." That goal, unfortunately, has yet to be achieved.
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A poster for the blockbuster film 2012, which premiered in 2009. DOOMSDAY IN THE MOVIES Movies with apocalyptic themes have long been a Hollywood staple. A 1951 film, WHEN WORLDS COLLIDE, depicted a catastrophic scenario in which a rogue planet on a collision course with Earth kills all but a few humans, who manage to escape in a spaceship and land on a new planet.
As the public fear of a nuclear confrontation between the U.S. and the Soviet Union grew, movie makers began to explore what might happen if such an event came to pass. The 1959 film ON THE BEACH, for example, depicted survivors of an all-out nuclear war waiting in Australia for deadly nuclear fallout to reach them, while 1965's DR. STRANGELOVE gave a glimpse of a grisly future in which post-nuclear survivors would practice polygamy in a mine-shaft shelter. The 1968 film PLANET OF THE APES depicted a future Earth in which nuclear war had reduced humans to an inferior species ruled by other primates. In the 1980s, as fears of a U.S.-Soviet showdown raged anew, made-for-TV movies such as THE DAY AFTER depicted the horror that might result from a "nuclear winter."
Home-Grown Invaders When the collapse of the Soviet Union in the early 1990s seemed to lessen the risk of nuclear war, movie makers found new visions of apocalypse. The TERMINATOR series depicted a future dystopia in which intelligent computers and robots turned traitorous and sought to exterminate their human makers, while the 1998 thriller ARMAGEDDON depicted a desperate attempt by astronauts to thwart a killer asteroid. In the 2007 film I AM LEGEND, a genetically-engineered virus, originally designed as a cancer cure, kills 90 percent of humanity, and turns most of the survivors into predatory vampires.
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An actor portrays a flesh-eating reanimated corpse, commonly known as a "zombie." ZOMBIE APOCALYPSE The zombie theme, which is loosely based upon Haitian legends of corpses who are revived and enslaved by voodoo priests, first emerged in the 1932 Hollywood film WHITE ZOMBIE, which starred Bela Lugosi as an evil sorcerer who turns a beautiful woman into his minion. But it was a 1968 low-budget film, director George Romero's NIGHT OF THE LIVING DEAD, which popularized the notion of a zombie apocalypse in which hordes of the undead overwhelmed civilization. In that film, a scientist speculates that the zombie outbreak was caused by radioactive contamination from a returning space probe, but in the slew of sequels made by Romero over the past four decades, that explanation has been dropped.
Why All The Zombies? Instead, zombie infestation simply becomes another dilemma that everyone is too busy dealing with to ponder the cause. The current American TV series THE WALKING DEAD which explores the struggle of a handful of survivors to escape a zombie pandemic, has become the most-watched series in the history of cable. Some have suggested that the idea of a fictional zombie outbreak resonates so strongly in the public imagination because it is a fantasy version of more tangible worries, such as fear of immigrants, downward economic mobility, and crime.
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In this cover art from the 1929 science fiction magazine "Amazing Stories," Martian war machines attack Earth's inhabitants. ALIEN INVASIONS The first book to depict an invasion of Earth by extraterrestrials bent on human destruction was Robert Potter's "The Germ Growers," published in England in 1892. But it was another, more commercially successful 1898 British novel, H.G. Wells' "War of the Worlds," that really caused the alien apocalypse fantasy to take hold.
Numerous movies, from 1953's INVADERS FROM MARS to the 1996 big-budget thriller INDEPENDENCE DAY, followed the same theme. It's seldom explained in such films why extraterrestrials would go to the trouble of journeying from a distant star system to attack humanity. But some legitimately fear that such an attack might occur.
Stop Inviting Aliens! Theoretical physicist and bestselling author Stephen Hawking told the Discovery Channel in 2010, for example, that he feared extraterrestrials might raid Earth for its natural resources, and warned that trying to make contact with civilizations on other worlds is, in his view, "a little too risky." According to the world-famous scientist, "If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn't turn out very well for the Native Americans."
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A star explodes, a common event throughout the universe, and one likely to be the real end of our planet sometime in the distant future. THE ULTIMATE END Astrophysicists, who've studied the life and death of stars, say that in about five and a half billion years, our Sun will run out of the hydrogen that it burns as fuel. That will be the start of a death spiral in which its core will shrink and its outer layers will expand massively, turning it into a red giant. In a final burst, the Sun will roast the solar system with a blast of heat that will temporarily turn even the usually frigid vicinity of Pluto and the Kuiper Belt into a celestial sauna. It’s likely that the inner planets, including possibly Earth, will be either sucked into the dying giant, or else turned into cinders.
On the plus side, it's unlikely that humans will still be on the planet to see their old neighborhood go up in flames. Over the next billion years, scientists predict that the sun's intensity will increase by about 10 percent, which will be enough to boil away the Earth's oceans and render the planet uninhabitable.