The old observatory stood two thousand yards above Los Angeles. The city’s lights flowed in rectangular waves about the foot of the hill, washing out the horizon with a salmon-pink glow; but the sky above was crisp and cool and peppered with stars.

The opened dome curved over Jays’s head, a shell of ribbing and panels that looked like the inside of an oil tank. The dome, with its brass fixtures and giant gears, smelled vaguely of old concrete. The telescope itself was an open frame, vaguely cylindrical, looming in the dark.

Sixt had taken one of his several doctorates, in astronomy, at UCLA, and had put in some observational work on this “scope. Now, his old contacts had made the place available for Sixt and his buddy, on this night of all nights.

Sixt was fussing around the telescope. “This is the Hooker telescope,” he said. “When it was built, in 1906, it was the largest telescope in the world… Kind of ironic.”

Jays had a pair of Air Force binoculars around his neck, big and powerful. He lifted them to the Moon, squinting through the aperture in the dome.

“What’s ironic?”

“The use of that bunker-buster.”

“The what? Oh, the bomb on the Moon.”

“Those conventional earthquake bombs they used in the Gulf War were too good. So the pariah states started buying up deep excavation equipment, to escape the bombs, and bury their command posts and their nuclear and chemical and biological stockpiles…”

Jays stared at the old Moon until the muscles at the edges of his eyes started to ache. He didn’t know what to expect, tonight. Would the changes on the Moon be visible at all, from a quarter-million miles? Would it be over in the blink of an eye?

“…The B61-11 is like a nuclear dum-dum bullet,” Sixt was saying. “It directs most of its damage straight down into the ground, towards the bunker. It can do as much damage in that way as an H-bomb. So it’s a nuclear weapon with a role for which conventional weapons are useless. It blurs the line between conventional and nuclear war.” He laughed. “Saddam’s super-bunkers probably never existed anyhow. Do you remember Doctor Strangelove? We managed to get ourselves into a deep-mining arms race…”

“What?” Jays looked at him vaguely, a little dazzled by Moonlight; he’d heard maybe one word in three. “What are you talking about?”

And so, he missed the moment of detonation.

…And Henry thought he felt the shock of the detonation: the gentlest of tremors transmitted through the layers of his suit, waves in the rock, passing through the silent heart of the Moon, from an explosion the planet’s width away.

He should get back to the shelter in the lava tube. He turned and loped over the regolith, rock flour deposited by billions of years of meteorites, lunar ground never broken by a human footstep before.