Predicting the end of the world has practically become a spectator sport. From movies like "Deep Impact" and "2012," to the Mayan prophecy, there are plenty of suggestions of how life on Earth could disappear. On closer inspection, not all of them pan out.
Here are some of the more popular predictions.
Asteroids: Scientists believe that a six-mile-wide asteroid wiped out the dinosaurs some 65 million years ago, leading some to want to keep a close eye on flying space debris that could be headed toward Earth. There have been plenty of near misses: Last summer, a rock the size of a bus buzzed Earth, passing the planet a mere 7,500 miles away.
In November 2011, an asteroid the size of an aircraft carrier came within 201,000 miles of the planet, wowing scientists and worrying end-of-the world types. And except for those in sci-fi flicks like "Armageddon," the last asteroid to cause damage to Earth was back in 1908. The impact from a meteorite over a remote region of Siberia flattened a forest the size of Tokyo.
The velocity of a speeding meteor is what could cause the most damage. A NASA scientist told Yahoo! News, "Even relatively small asteroids could cause the damage equivalent to a very large nuclear weapon if they were to strike the Earth." Chances of an asteroid hitting Earth with that kind of damage are remote.
The Rapture: Christian radio broadcaster Harold Camping had to resign his position after wrongly claiming he had cracked the Biblical code for the day the world would end. He wrote that on May 21, 2011, and again on October 21, "the believers in Christ who have not experienced physical death will be changed into their glorified bodies. At that time, they will be caught up in the air to be with Christ."
When both dates came and went without an apocalypse, Camping issued an apology and retired from Family Radio. He noted, "We also openly acknowledge that we have no new evidence pointing to another date for the end of the world."
On December 21, 2012, Earth will be in exact alignment with the sun and the center of the Milky Way galaxy -- an event that takes place once every 25,800 years. The ancient Mayans were thought to believe that this could be catastrophic -- and the potential consequences were the inspiration for the movie "2012."
However, researchers now suggest that the date was simply marking the end of the Mayan calendar, not a prophecy of doom.
Zombies: OK, an infection that causes the dead to become undead doesn't actually exist. But imagine a deadly virus, one for which there is no cure, spreading around the world. In the 14th century, the bubonic plague wiped out half the people in the populations it touched.
Diseases that spread from animals to humans, like SARS, avian flu, and swine flu (as portrayed in the film "Contagion"), have become bigger threats as people encroach on previously uninhabited areas. Superbugs -- drug-resistant pathogens -- can attack, and there's no immediate antidote.
Supervolcano: Make no mistake, if a big one blows, it could have dire consequences. How do we know this? Because about 75,000 years ago, that's what happened at Mount Toba in Sumatra, Indonesia. Some scientists theorize that so much ash blew into the atmosphere that the light of the sun was blocked, resulting in an ice age that destroyed plants and populations.
The largest eruption in recorded history is Krakatoa, Indonesia, in 1883. The explosion could beheard around the world, caused a "volcanic winter" that led the global temperature to drop, and resulted in the deaths of more than 36,000 people.
If one of the prehistoric volcanoes erupted, such as the Yellowstone caldera in Wyoming, an epic disaster could result, covering half the country in a layer of ash, killing livestock, and threatening the lives of thousands.