Of course I know that. “Yes, Dad.”

“People used to think the Moon was like the Earth. They gave those dark grey patches the names of oceans. Well, now we know they are seas of frozen lava. Think about that. And those brighter areas are the highlands, rocky and old. Now, look for the Man’s right eye: you see it? That distinct circle? That’s what we call the Mare Imbrium. It’s actually one huge crater, big enough to swallow Texas. It was gouged out by a gigantic meteorite impact almost four billion years ago. What a sight that must have been.”

“But there was nobody around to watch it. Not even the dinosaurs.”

“That’s right. And then, much later, it got flooded with basalt—”

“Where did Neil Armstrong land?”

“Look for the Man’s left eye. See the way it’s sort of sad and drooping? Follow that eye down and you come to Mare Tranquillitatis.”

“Tranquillity Base.”

“That’s right. Neil put his LM down just by the Man’s lower eyelid.”

“Can I see your crater?”

“No. Most craters are too small for people to see. But I can show you where it is. Look again at that big right eye. See the way the mare’s grey extends beyond the circle, out of the Imbrium basin itself? That’s Procellarum, the Ocean of Storms. That’s where Apollo 12 landed, where Pete Conrad put his LM down right next to that old Surveyor. Well, my crater is on the border there, between Imbrium and Procellarum.”

“I can’t see it.”

“It’s called Aristarchus. It’s named after the man who figured out how far away the Moon is, two thousand years ago…”

She looked at his pointing hand. Even though he had washed and showered, over and over, she saw there was still black Moon dust under his fingernails, and ground into the tips of his fingers. It was going to take a long time for him to get clean.