End of an Era

Through the binoculars I could see other evidence that this was indeed a younger Luna. I looked at where Giordano Bruno should have been. Normally, that crater is right on the limb of the full moon, but here it should have been well in from the edge of the disk. As I suspected, its series of 500-kilometer-long rays was nowhere to be found. Five British monks in a.d. 1178, their faces tipped toward the heavens, had actually seen the meteor impact that had made that crater.

I thought about mentioning the missing crater to Klicks, but talk of meteor strikes always sparked the debate between us about whether one such had caused the Cretaceous-Tertiary extinctions. Klicks bought that theory. In the eyes of the general public, that made him right in line with mainstream thinking. After all, the newspapers and PBS shows in the 1980s had all concluded that an asteroid impact was indeed the culprit. I wasn’t in the mood to rehash it all again — I’m more inclined to lock horns with Klicks after a few brews, and, sadly, there were none among our provisions — but then something happened that brought up the old debate anyway. Slowly, quietly, without any fuss, a second moon was rising after the first. It was smaller, only about a third the apparent diameter of Luna. Spherical, it too was waxing gibbous, looking like a white jelly bean.

"Klicks?" I said.

"I see it."

I brought my binoculars to bear on the tiny orb, but its face was too small to show any detail. "Trick," I said, surprising myself. "I think we should call it Trick."

"After Charles Trick Currelly, no doubt," said Klicks, wanting to demonstrate that he got the reference. C. T. Currelly, an early-twentieth-century archaeologist, was the founder of the Royal Ontario Museum, where I worked. One of my occasional forays into the world of popular writing had been a biography of him for Rotunda, the ROM’s member magazine. Klicks did not dispute my choice of name and I was grateful for that small miracle.

We watched the two moons for some time. It seemed that Trick was catching up with Luna, meaning that it was in a much lower orbit. Since Luna is tidally locked, so that the same side always faces Earth, that would mean that Trick probably was also. It must be under a lot of gravitational stress being that much closer…

Aha!

"There goes the periodic extinction theory," I said, excitement in my voice.

The Alvarez Group at Berkeley published their asteroid-impact extinction theory in Science in 1980. About the same time, an interesting hypothesis was making the rounds concerning the Eocene-Oligocene extinctions, the ones that would come 30 million years after the demise of the dinosaurs. According to it, those later extinctions resulted from a general cooling caused by the breakup of an ancient second moon, leaving Earth with a temporary equatorial ring of orbiting debris that blocked enough sunlight to lower temperatures for a million years or so. The Alvarez theory, sexy because it dealt with dinosaurs and embraced by many pop-science communicators after Sagan had linked it to nuclear winter, eclipsed the ringed-Earth discussions.

Others, including Klicks, tried to push the Alvarez theory a step further, claiming that bolide impacts at regular intervals, caused perhaps by a dark star periodically disturbing either the asteroid belt or the Oort cloud, were responsible for a regular schedule of extinctions, including both the K-T and the E-O. That idea never washed with me, since to get the 26-million-year periodicity you had to use the late Ordovician dyings, which were obviously just the result of plate tectonics moving the supercontinent Gondwanaland over the south pole, causing an ice age.

Klicks knew my position on all of that, of course, so I simply pointed at the second moon. "Trick provides a one-of-a-kind explanation for the Eocene-Oligocene extinctions," I said. "There’s nothing periodic about a moon breaking up."

To his credit, Klicks didn’t contest that. But he did say, "Why link it to those deaths? Why not to the ones that are about to occur?"

"Tektites," I said, referring to the glassy, moon-like rocks found at various locations on Earth. "The age of the southeastern U.S. tektite field coincides with the E-O boundary. I bet they were caused by the impacts of the remnants of Trick."

Klicks was quiet for a minute or so, although I could hear him grinding his teeth in the dark, the way he does when he’s thinking — chewing over a problem, you might say. Finally he spoke. "We have sleeping pills."

"Huh?" I guess the change of subject meant I had won that round, but I couldn’t see what he was getting at.

"I said, we could take something to get to sleep. We’re going to be useless in the morning if we stay awake all night."