'mega' asteroid threatening earth
A 'global killer' could collide with Earth as soon as 2020, wiping out life as we know it and changing the climate for millennia.
If something like this happened, depending on where it hit it would be absolutely life-altering. The atmospheric chemistry would be upset by cutting out sunlight. It would be like a nuclear winter and could last for tens of thousands of years.
small comets [...] capable of collapsing civilisation.
These comets are
200-300km (186 miles) in diameter they are sheer monsters and could sterilise the earth if we are hit by one. [...] These things are floating around in the sky and there is a real hazard out there that hasn't been properly studied, and it could happen at any time.
Experts predict that asteroids are to pepper the planet from 2017
NASA revealed disturbing new data showing 400 impacts are expected between 2017 and 2113, based on new observational data [...] NASA says an impact by one of these "in the wrong place" would be a catastrophe, but it would not threaten civilisation.
The working group warned an impact by an asteroid larger than
1-2 kilometres could throw the climate into chaos triggering crop failure and loss of life. An impact by an object larger than about
5 kilometres is damaging enough to cause mass extinctions, it said.
Source:
Planet earth faces 100 YEARS of killer strikes starting in 2017