Just in case anyone hasn’t seen the news in the last four days, a 56ft-wide asteroid weighing around 10,000 tons and travelling at 40,000 miles per hour entered the Earth’s atmosphere over Russia on February 15th. (At which point it became a meteor, not an asteroid, I’ve learned.)
It disintegrated under the force of atmospheric pressure nine miles over the city of Chelyabinsk, causing a shockwave that shattered windows across the city and injured 1200 people.
This write-up at the New Yorker sums it up pretty well, and io9 has some science here.
The key lesson in all this? Space is very big, and IT IS TRYING TO KILL US.
DAN HARRIS: 10% SCI, 90% FI 
And yet it is NOT the asteroid which passed Earth inside the outer satellite orbit that was the size of a football field. It’s apparently unrelated. Space had two shots at us. Good thing the bigger one missed, right?
I know, it’s crazy! And I did find it funny how lots of people assumed the two were related. As if the big asteroid had somehow sent a little asteroid ahead as a vanguard in its bid to destroy the Earth. And then comically missed 🙂