Analysis - Don't look now - but we are currently experiencing a rash of stories about a forthcoming global catastrophe. But in a change from reports of pandemics and climate change, this global catastrophe is produced by the impact of a giant asteroid. Or comet. Or both. This may feel extra ominous given the events in the recent Netflix film "Don't Look Up", in which the Earth is threatened by a "planet killer" asteroid. But how worried should we really be - and what would happen if such a body actually hit us?