We detected it five hours before impact.

That we even had that much warning was sheer luck. A Chinese sensor drone left over from the Helium Wars felt its gravitational wake as it passed through Neptune’s orbit, five tons of depleted uranium accelerated to three-quarters of the speed of light, like a speedboat through calm waters. News of its arrival, encoded in pulses of laser light aimed for receivers in the inner system, reached human eyes just a little more than an hour before it did.

What would you do in Earth’s final hour?

If you’ve played any of the feelies about The Day, you probably think you know what it was like, when it hit just south of Paris, but you don’t. It was nothing like that, no ominous clouds, no darkening of the sky, no fireball growing larger and larger. It just happened, in far less than the blink of an eye. Two seconds before impact, it was outside the moon’s orbit. One second before impact, it was still more than 200,000 kilometers from the Earth. And then—

Impact.

The next one was detected a few hours later.