Chelyabinsk may be remote for most people reading this, but the anniversary is an important reminder for all of us of the potential hazards of Earth meeting an asteroid or comet.
Astronomers estimate that they have found over ninety percent of near earth objects over 1 km in size. Comforting, I suppose, but that still leaves a number of ones we don't know about. Not to mention ones smaller than 1 km that could cause substantial local damage.
The Planetary Society website says "Over the next three centuries, there is a 1 in 30 chance that a Tunguska-like impact will result in some human casualties." This was written before Chelyabinsk whose asteroid was smaller than the Tunguska object. No one was killed, but around 1500 people had injuries that made them get medical attention.
Alan Fitzsimmons, who spoke at European Astrofest recently, says that we need to revise upwards our estimates for the likelihood of an impact.