The Spaceguard Centre & Observatory

Don Yeomans: An asteroid or comet larger than a kilometer colliding with the Earth would be a very rare event.

Images sent back from space missions suggest that smaller asteroids are not pristine chunks of rock, but are instead covered in rubble that ranges in size from meter-sized boulders to flour-like dust.

Recreating how the seeds of life might have survived aboard an ancient meteorite that crashed to Earth is no small feat, but scientists have begun doing just that in a recent lab experiment.