For those who fear that the world will end on December 21, the question is, how? Could a black hole suck in the whole solar system? Well, yes, hypothetically, it could, but we'd probably see it coming. That's because supermassive black holes are extremely rare and if one was approaching Earth, scientists would have noticed decades ago.
It was an asteroid about 10 kilometers (6 miles) in diameter that ended the age of dinosaurs 65 million years ago. If one of similar size struck the Earth again it would hurl tons of rock and dust into the air, and the atmosphere would be entirely transformed making the planet a cold, dark place - and make human life incredibly difficult.
In the 1984 film "The Terminator," a computer network makes itself independent and then starts a war against mankind. Artificial intelligence frightens a lot of people. Will humankind be destroyed by its own creations? Regardless of the answer, a malicious computer with its own consciousness could cause a lot of harm to our digital world.
But we humans don't need intelligent machines to exterminate life as we know it. Nuclear weapons are capable of doing that. The Cold War is over, but the danger is still there - tens of thousands of nuclear weapons belong to nine countries.
A supervolcano with a massive magma chambers erupts, causing immense destruction, earthquakes, tsunami and catastrophes around the world. The last supervolcano erupted in New Zealand 32,000 years ago. There are several supervolcanoes on the planet, including the Phlegraean Fields near Naples, Italy and Yellowstone National Park in the United States.
The Earth has undergone prolonged ice ages in which species became extinct. Would there be another ice age if the Gulf Stream dried up? A small part of the warm ocean current, which raises temperatures in Europe, could cool off in 100 years - at the earliest, experts warn. If that happened, temperatures could fall by a few degrees in Europe.
While what are pictured here are just props from the set of a movie, the plague and other deadly pandemics do have a history of wiping out swathes of the Earth's population. Thanks to antibiotics, these diseases are now generally treatable. But bacteria are adaptable and are continually mutating into new, drug-resistant strains. That makes death by disease a possible future for the world.
A virus or bacteria revives the dead who then thirst for human flesh - preferably brains. The zombie apocalypse is a recurring theme in countless books and horror films. But there is no scientific evidence that would prove the existence of zombies. Still, the CDC, the US health authority, has prepared a tongue-in-cheek emergency plan in case of a zombie apocalypse.
The Earth's magnetic field protects it from a stream of energetic charged particles released by the sun. The northern lights occur when the particles collide with the Earth's magnetic field. Without it, the Earth would be as lifeless as the moon. The magnetic field could weaken in 2,000 years, experts say. The transition period could be very dangerous.
The world will end one day - at the very latest when the sun's energy has burned up and it collapses into a giant red giant star that consumes the Earth. That is, if we don't do ourselves in over the next few billion years.
Hundreds of years ago, people thought that the world was ending whenever there was a solar eclipse. Now, people fear artificial intelligence, nuclear war and germs. What will man fear in a thousand years?
The world is supposed to end on December 21, at least according to the Mayan calender. DW looks at how an apocalypse could play out, now or in the future.