How realistic is the world end in 2012?

The doomsday stories seem to be closely connected with the year 2012, especially since the ancient Mayan calendar which covers the timespan of more than 5000 years, ends on December 21st 2012. This day will mean the end of the 13th bak'tun, last period of around 400 years in Mayan calendar.

While there is a certainly truth that the Mayan civilization knew whole lot of things about astronomy there's no evidence whatsoever, that the December 21st 2012 means the end of the world, it only means the end of Mayan calendar and nothing else.

The most popular doomsday theory connected with Mayan calendar is the one about the infamous planet Nibiru that was supposedly discovered by the ancient Sumerians. Under this theory the planet Nibiru should collide with Earth in 2012, and even if it doesn't hit our planet its passage through our Solar system would cause fatal damage to our planet.

This astronomical disaster was first announced for 2003, and after that it was postponed to December 2012 in order to match with Mayan calendar.

The NASA scientists have announced several times that if such planet would actually be on course to collide with earth they would be able to monitor it for at least couple of decades and today we could be even able to see this planet with naked eyes.

The increased solar activity is also no reason for panic in 2012 because even the almighty Sun doesn't have enough energy to send a killer solar flare 93 million miles to destroy Earth.

There also seems to be no big asteroid heading our way. Even the infamous 2005 YU55 asteroid hasn't done any damage to our planet when it passed next to Earth in November 2011, and according to NASA there are no deadly asteroids currently heading our way though some tabloids were even suggesting that NASA hides the truth about this asteroid hitting our planet.

From the astronomical point of view there seems to be no danger whatsoever, in terms of possible disaster that would end all life on our planet in 2012. Instead of worrying about the cataclysmic scenarios world should rather start worry about the long-term effects of climate change because this looks to be the only real threat that could seriously disrupt our future life on Earth.