Like the comet that restarted the evolutionary life cycle 65 million years ago (give a take a decade or two, because, well, scientists), one icy rock is approaching Mars
Given the unusual speed of the comet (which is moving so fast that it may well be coming from outside the solar system—cool upon cool) and the fact that it is travelling the wrong way round the sun, from a planet’s point of view, Mr Plait estimates that its impact should yield a blast equivalent to that of a billion megatons of TNT. It would be an event on the same sort of scale as the impact that drove the dinosaurs extinct 65m years ago. If it really is that big, and if the comet were to hit the side of Mars facing Earth (it seems that it might do, but it might also hit the far side), then the blast could well be visible to the naked eye, even in daylight.
Unfortunately, there is only a small chance that this might happen; however, if it does, it would be nice to have the Curiosity on the ground.
Wonder if we can name the comet, Cat.