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Reminder: The *average* bolide impact velocity at Earth is 20 km/s. That's five seconds from the Kármán line to the ground. There's no slow movement of an asteroid through the sky, giving you enough time to say goodbye to your loved ones. One moment you're alive, the next you're on fire.

That's the *average* speed. Some impactors will be slower, others faster. Comets are probably going to be faster than asteroids. For a sufficiently high speed, the lithosphere will become molten.

To be clear, I don't spend any time worrying about something smashing into us. (There's lots of other things to be worried about.) I just don't want you to think that we'd have any time to watch the thing enter the atmosphere, because we wouldn't.