When Jupiter’s tides ripped Comet Shoemaker–Levy 9 to shreds, only for the icy chunks to succumb to the intense Jovian gravity, ultimately slamming into the gas giant’s atmosphere, mankind was treated to a rare cosmic spectacle (in human timescales at least). That was the first time in modern history that we saw a comet do battle with a planet… and lose.
But next year, astronomers think there’s a chance — albeit a small one — of a neighboring planet getting punched by an icy interplanetary interloper. However, this planet doesn’t have a generously thick atmosphere to soften the blow. Rather than causing bruises in a dense, molecular hydrogen atmosphere, this comet will pass through the atmosphere like it wasn’t even there and hit the planetary surface like a cosmic pile-driver, ripping into the crust.
What’s more, we’d have robotic eyes on the ground and in orbit should the worst happen.