“Yáo Li-Jie,” I say. I don’t know how I remembered his given name. It just came to me in the moment. “I commend your body to the stars.”

The airlock cycles and I am alone. I was alone all along, but now I am truly alone. The sole living human within several light-years, at least.

What do I do now?

“Welcome back, Mr. Grace!” said Theresa.

The kids all sat in their desks, primed for science class.

“Thanks, Theresa,” I said.

Michael piped in. “The substitute teacher was booooring.”

“Well, I’m not,” I said. I picked up four plastic bins from the corner. “Today we’re going to look at rocks! Okay, maybe that is a little boring.”

A chuckle from the kids.

“You’re going to divide into four teams and each team will get a bin. You have to separate the rocks into igneous, sedimentary, and metamorphic. First team to finish—and get every rock correctly categorized—gets beanbags.”

“Can we pick our own teams?” Trang asked excitedly.

“No. That just leads to a bunch of drama. Because children are animals. Horrible, horrible animals.”

Everyone laughed.

“Teams will be alphabetical. So the first team is—”

Abby raised her hand. “Mr. Grace, can I ask a question?”

“Sure.”

“What’s happening to the sun?”

The whole class suddenly grew much more attentive.

“My dad says it’s not a big deal,” Michael said.

“My dad says it’s a government conspiracy,” said Tamora.

“Okay…” I set the bins down and sat on the edge of my desk. “So… basically, you know how there’s algae in the ocean, right? Well, there’s sort of a space algae growing in the sun.”

“Astrophage?” said Harrison.

I almost slipped off the desk. “Wh-Where did you hear that word?”

“That’s what they’re calling it now,” said Harrison. “The president called it that in a speech last night.”

I’d been so isolated in that lab I didn’t even know the president had given a speech. And holy cow. I invented that word for Stratt the day before. In that time it got from her to the president to the media.

Wow.

“Okay, yes. Astrophage. And it’s growing on the sun. Or near it. People aren’t sure.”

“So what’s the problem?” Michael asked. “Algae in the ocean doesn’t hurt us. Why would algae on the sun?”

I pointed to him. “Good question. Thing is, Astrophage is starting to absorb a lot of the sun’s energy. Well, not a lot. Just a tiny percentage. But that means Earth gets a tiny bit less sunlight. And that can cause real problems.”

“So it’ll be a little colder? Like a degree or two?” Abby asked. “What’s the big deal?”

“You guys know about climate change, right? How our CO⁠₂ emissions have caused a lot of problems in the environment?”

“My dad says that’s not real,” said Tamora.

“Well, it is,” I said. “Anyway. All the environmental problems we have from climate change? They happened because the world’s average temperature went up one and a half degrees. That’s it. Just one and a half degrees.”