Schoolboy corrects Nasa calculation

1 in 450 chance of asteroid impact (Science | guardian.co.uk)

"Both Nasa and Nico agreed that the asteroid would create a ball of iron and iridium 320 metres wide and weighing 200bn tonnes, which would crash into the Atlantic, if it collided with Earth. The impact would create huge tsunami waves, destroying coastlines and inland areas while creating a thick cloud of dust that would darken the skies indefinitely."

No more Willesden sunsets, then.