The dinosaurs were snuffed out in a geological instant (well not exactly, but that is a popular image).  The Chicxulub bolide, its girth 10-15 kilometres, collided with Earth 65 million years ago, leaving a 150 kilometre-wide crater and enough dust and aerosols in the upper atmosphere to darken latest Cretaceous skies for decades.

Like all planetary bodies in our Solar System, Earth has received its share of meteorite and comet impacts. We still bear the scars of some. Every day, bits of space dust and rock plummet towards us – most burn up on entering the atmosphere, but a few make it to the surface. Occasionally they even startle us with air-bursts – Tunguska in 1908,  Chelyabinsk (2013), both in Russia. But humanity has never witnessed a decent sized impact, at least in recorded history. It’s all theoretical. Continue reading →