Nalaka Gunawardene, a friend and colleague, has provided an overview of the hazards posed by near-earth objects.
Thousands of pieces of cosmic debris enter our atmosphere every day — most are burned up before hitting the ground (producing harmless ‘shooting stars’). Larger pieces that crash-land are called meteorites. Even then, average ones are too small to cause much damage.
Once in a while, a large enough piece comes along — as did on February 15 – which can be an asteroid or part of a comet. Called Near Earth Objects (or NEOs), some of these may pose an impact danger.
Astronomers constantly scan the skies to find NEOs long before they hit. The effort, which involves telescopes and teams around the planet, is aptly called the Spaceguard – a term coined by Arthur C Clarke 40 years ago in his science fiction novel Rendezvous with Rama (1972).