Here is the story.
http://www.universetoday.com/99801/45-m ... on-feb-15/
It describes an asteroid which is due to pass very close to earth on Friday, mentioning
No known asteroid has ever passed so near to Earth.
I believe that in fact some known asteroids have passed closer to Earth, shortly before crashing into it, but I'll assume they either mean "within recorded history" or "without crashing into Earth immediately thereafter". So no worry there. But of particular interest is this quote.
So the local effect on human cities for example of a 50 meter wide asteroid impact would be deadly and utterly devastating. But it would not be catastrophic to all life on Earth. Nevertheless, at this moment, Earth has no defenses against asteroids other than talk.
What's that? Talking is a defence against asteroids? Should we all be talking Friday? Do we need to talk at the same time? Do we need to say the same things? In the same language?
The article is quite sketchy on this point.