Humanity survived the hype and dread of the Judgment Day of 1844, the deadly Halley's Comet which almost hit the planet in 1910 with its toxic tail, and the cataclysmic digital failure popularly known as Y2K in 2000. However, for some mysterious reasons, people seem to crave for fresh doomsday predictions as the older episodes and dates are forgotten.

According to social scientists, apocalyptic prophesies raise a considerable amount of human interest, simply because they sound rational when they are tied to otherwise unknown or mystical subjects like time, space and human existence.

The year began with renewed interest in the next landmark in the history of doomsday predictions -- Dec. 21, 2012 -- because this is the day when Mayan Calendar, or the system of calendars used in pre-Columbian Mesoamerica, apparently ends.  Despite the fact that Mayans didn't predict apocalypse in 2012, strange and scientifically implausible theories on the end of human civilization have been doing the rounds.

Here is a roundup of the most widely circulated, and weirdest theories surrounding the 2012 doomsday prediction:

1. Planet Nibiru: It is a planet-sized object which, according to believers, is set to collide with the Earth in 2012, and is under NASA surveillance, which the U.S. government is keeping a top secret.

Planet Nibiru, sometimes referred to as Planet X, is the brainchild of Nancy Leider, founder of the website ZetaTalk, who describes herself as a contactee who can receive messages from extra-terrestrial life. Leider said a collision with Planet Nibiru would destabilize Earth's pole, which would subsequently displace the Earth's crust.

Scientists have rebuffed the idea of the invisible Planet Nibiru, and have successfully debunked the conspiracy theories surrounding its existence and trajectory.

2. Mass Extinction:  Some doomsday theorists say that there is a pattern to the mass extinctions that have occurred over the ages in Earth's history. It is being speculated that the mass extinctions occur every 26 million years, due to the vertical oscillations made by the Sun as it orbits the galactic center, regularly passing through the galactic plane.  The shift in Sun's position increases the likelihood of galactic collisions leading to mass extinction of species.

However, scientists reject the theory saying that the supposed alignment takes place over tens of millions of years, and could never be timed to an exact date. Scientific evidence, based on Sun's galactic position, doesn't suggest any sort of apocalyptic realignment at least for another ten million years.

3. Death of Betelgeuse:  Speculators have tried to connect the impending death of a red supergiant star named Betelgeuse to the final stages of the Earth. Even though the Betelgeuse is set to undergo a supernova at some point in future, it can never be a threat to the Earth, as the star is approximately 600 light years away, thus making it a scientific impossibility for the Earth to be affected by the explosion.

4. Alien Invasion:  Conspiracy theorists claim that SETI, a collective name for search for extraterrestrial intelligence, have detected three large alien spacecrafts due to arrive on the Earth in 2012. However, in January 2011, Seth Shostak, chief astronomer of SETI, issued a press release debunking the claims.

5. Geomagnetic Reversal: Another idea tied to the end of the world in 2012 involves pole shift or geomagnetic reversal, a term used to refer to the reversal of the Earth's magnetic south and north poles.

Proponents claim that the reversal could be triggered by a massive solar flare releasing the energy equivalent to 100 billion atomic bombs. Scientists reject the claims saying that geomagnetic reversals span up to 7000 years and don't start on a particular date. Evidence suggests that the solar maximum has nothing to do with geomagnetic reversals, which is driven by forces confined to the Earth.

6. God's Destructive Incarnation:  Indian mythology says that Lord Kalki, or the destructive incarnation of Lord Vishnu, will degenerate the Earth in 2012, marking the end of the final phase of time in Earth's current cycle, known as the Kali Yuga.

Over 15 million people believe that Lord Kalki has already been born, in 1998, and is preparing to destruct earth this year.

7. Esoteric French Village: A small village of Bugarach, which became popular in 1960s and 70s with the hippie movement, is being touted as the only place on the Earth that would be spared in the 2012 apocalypse.

The New Age believers claim that the local mountain, Pic de Bugarach possesses mystical powers to save thousands of people who may swarm the village to avoid death and destruction.

In 2011, the local mayor, Jean-Pierre Delord, said that the town would be overwhelmed by the visitors in 2012, and suggested he may call in the army.

8. Timewave Zero: Terence McKenna, an American philosopher and psychonaut, devised a numerological formula that claims that the universe will reach Infinite Complexity in 2012. He calculated the end date as November 2012 based on the atomic bombing of Hiroshima. However, he later revised the hypothesis to match with the end of Mayan calendar in December 2012.

9. Web Bot Prediction: A computer program known by the name Web Bot project predicted doomsday in 2012 based on Internet chatter. Even though the programmers have claimed that the Bot has successfully predicted several natural disasters, critics reject the claims saying that Internet chatter may predict manmade disasters like stock market crash, but not natural disasters.

10. Photon Belt: According to beliefs linked largely to the New Age movement, belts or rings of photons are going to envelop the Earth causing apocalypse or a spiritual awakening. However, scientists say that photons forming belts is a physical impossibility, as photons always travel in straight lines.