Asteroid impact risks 'underappreciated'
A visualisation showing where sizeable asteroids have hit the Earth in recent years has been released by the B612 Foundation.
The US-based group, which includes a number of former Nasa astronauts, campaigns on the issue of space protection.
It hopes the visualisation will press home the idea that impacts are more common than we think.
B612 Foundation CEO Ed Lu talks to our science correspondent Jonathan Amos.
22 Apr 2014