Her eyes went wide. “Oh my God,” she said, shaken. “What . . . what happens now?” she asked.

I shrugged a little. “More tests. The diagnosis was made based on material in my sputum, but they’ll want to do biopsies and other tests to determine . . . determine how far it’s spread.”

“How?” she said, the syllable quavering.

“How did I get it?” I shrugged. “Noguchi figures it was all the mineral dust I’ve inhaled over the years.”

“God,” said Susan, trembling. “My God.”

Donald Chen had been with the McLaughlin Planetarium for ten years before it was shut down, but unlike his colleagues, he was still employed. He was transferred internally to the ROM’s education-programs department, but the ROM had no permanent facilities devoted to astronomy, so Don had little to do — although the CBC did put his smiling face on the tube every year for the Perseids.

Everybody on staff referred to Chen as “the walking dead.” He already had an awfully pale complexion — occupational hazard for an astronomer — and it seemed only a matter of time before he would be given the boot from the ROM, as well.

Of course, the entire staff of the museum was intrigued by the presence of Hollus, but Donald Chen had a particular interest. Indeed, he was clearly miffed that the alien had come looking for a paleontologist rather than an astronomer. Chen’s original office had been over in the planetarium; his new office, here in the Curatorial Centre, was little more than an upright coffin — but he made frequent excuses to come visit me and Hollus, and I was getting used to his knocks on my door.

Hollus opened the door for me this time. He was now quite good with doors and managed to manipulate the knob with one of his feet, instead of having to turn around to use a hand. Sitting on a chair just outside the door was Bruiser — that’s the nickname for Al Brewster, a hulking ROM security guard who was assigned full-time now to the paleobiology department, because of Hollus’s visits. And standing next to Bruiser was Donald Chen.

“Ni hao ma?”said Hollus to Chen; I’d been lucky enough to be part of the Canada-China Dinosaur Project two decades ago, and had learned passably good Mandarin, so I didn’t mind.

“Hao,”said Chen. He slipped into my office and closed the door behind him, with a nod to Bruiser. Switching to English, he said, “Hey, Slayer.”

“Slayer?” said Hollus, looking first at Chen, then at me.

I coughed. “It’s, ah, a nickname.”

Chen turned to Hollus. “Tom has been leading the fight against the current museum administration. The Toronto Star dubbed him the vampire slayer.”

“The potential vampire slayer,” I corrected. “Dorati is still getting her way most of the time.” Chen was carrying an ancient book, written in Chinese judging by the characters on the gold cover; although I could speak the language, reading it at any sophisticated level was beyond me. “What’s that?” I said.

“Chinese history,” said Chen. “I’ve been bugging Kung.” Kung held the Louise Hawley Stone chair in the Near Eastern and Asian civilizations department, another post-Harris-cutback amalgam. “That’s why I wanted to see Hollus.”

The Forhilnor tipped his eyestalks, ready to help.

Chen set the heavy book on my desk. “In 1998, a group of astronomers at the Max Planck Institute for Extraterrestrial Physics in Germany announced the discovery of a supernova remnant — what’s left behind after a giant star explodes.”

“I know about supernovas,” said Hollus. “In fact, Dr. Jericho and I were talking about them recently.”

“Okay, good,” said Chen. “Well, the remnant those guys discovered is very close, maybe 650 light-years away, in the constellation of Vela. They call it RX J0852.0-4622.”

“Catchy,” said Hollus.

Chen had little sense of humor. He continued on. “The supernova that formed the remnant should have been visible in our skies about the year 1320 A.D.Indeed, it should have outshone the full moon and been visible even during the day.” He paused, waiting to see if either of us would dispute this. We didn’t, and he went on. “But there is no historical record of it whatsoever; no mention of it has ever been found.”

Hollus’s eyestalks weaved. “You said it is in Vela? That is a southern constellation, both in the skies of your world and mine. But your world has little population in its southern hemisphere.”

“True,” said Chen. “In fact, the only terrestrial evidence we’ve found at all for this supernova is a nitrate spike in Antarctic snow that might be associated with it; similar spikes correlate with other supernovae. But Vela is visible from the land of my ancestors; you can see it clearly from southern China. I’d thought if anybody had recorded it, it would be the Chinese.” He held up the book. “But there’s nothing. Of course, 1320 A.D.was in the middle of the Yuan dynasty.”

“Ah,” I said sagely. “The Yuan.”

Chen looked at me as though I were a Philistine. “The Yuan was founded by Kubla Khan in Beijing,” he said. “Chinese governments were normally generous in their support of astronomical research, but during that time, science was cut back while the Mongols overrode everything.” He paused. “Not unlike what’s happening in Ontario right now.”

“Not bitter, are we?” I said.

Chen shrugged a little. “That’s the only explanation I could think of for why my people didn’t record the supernova.” He turned to Hollus. “The supernova should have been just as visible from Beta Hydri was it was from here. Do your people have any record of having observed it?”

“I will check,” said Hollus. The simulacrum stopped moving; even the torso stopped expanding and contracting. We waited about a minute, and then the giant spider came to life again, Hollus reinhabiting his avatar. “No,” he said.

“No record of a supernova 650 years ago?”

“Not in Vela.”

“Those are Earth years, of course.”

Hollus sounded offended at the suggestion that he might have screwed up. “Of course. The most recent naked-eye supernova observed by either the Forhilnors or the Wreeds was the one in the Large Magellanic Cloud about fifteen years ago. Before that, both races saw one in the constellation you call Serpens, in what would have been very early in your seventeenth century.”

Chen nodded. “Kepler’s supernova.” He looked at me. “It was visible here starting in 1604. It got to be brighter than Jupiter, but you could barely see it during the day.” He pursed his lips, thinking. “That’s fascinating. Kepler’s supernova was nowhere near Earth, or Beta Hydri, or Delta Pavonis, and yet all three worlds saw it and recorded it. Supernova 1987A, of course, wasn’t even in this galaxy, and we all recorded it. But the Vela event of circa 1320 was quite nearby. I’d have thought someone would have seen it.”

“Perhaps a dust cloud intervened?” said Hollus.

“There’s no dust cloud in the way now,” said Chen, “and it would take a cloud either awfully close to the star that blew up or awfully big to obscure the view from Earth and Beta Hydri and Delta Pavonis. Somebody should have seen this thing.”

“Quite a puzzle,” said Hollus.

Chen nodded. “Isn’t it, though?”

“I would be glad to provide you with what information my kind have gathered about supernovas,” said Hollus. “Perhaps it will shed some light on the issue.”

I wondered if Hollus was deliberately making a pun.

“That would be great,” said Chen.

“I will have some material sent down from the mothership,” said Hollus, eyestalks waving.

When I was fourteen, the museum had had a contest for children interested in dinosaurs. The winner would get all sorts of paleontology-related prizes.

If it had been a dinosaur trivia contest, or a test of common knowledge about dinosaurs, or if it had required kids to identify fossils, I would have won, I’m sure.