Will a comet strike Mars next year?
What's bad news for Mars would be good news for Earth-bound scientists.
Observing such an impact, which might leave a crater hundreds of kilometres across, would be a huge scientific boon. Of the geological processes which shape the surfaces of planets, impacts are the ones that humans have had the least opportunity to observe up close. The faces of the moon, of Mars and of Mercury show the aftereffects of such impacts, but the processes by which they hollow out their craters and raise their rims and central peaks have only been witnessed in miniature.