“Of course not. I don’t expect you to stay in this house all summer.” Joan sat down on a stool in front of the counter. Several rolling file cabinets were tucked beneath it, but a couple were pulled out, their drawers open to reveal hanging files. “But while you’re here, maybe you could help me with something.”

“Sure.” I glanced at the far end of the room, where a lumpy structure on a wheeled cart was covered with a cloth. I thought Joan was going to uncover it to show me, but she gestured to a stack of folders on the counter.

“These are your grandfather’s research notes from Boulder. Class lectures. Observations and research. Drafts of papers. Correspondence.”

Grandpa had taught astronomy at the University of Colorado in Boulder in the seventies and early eighties, before moving to Berkeley in the mid-eighties.

“Why are you going through his notes?” I asked.

“It’s part of the process. You’re still planning to major in astronomy, right?”

“Yes. Well, I have to decide if I’m going to major in physics or EAPS—earth, atmospheric, and planetary sciences. MIT doesn’t have a major in astronomy, technically.”

She smiled. “You sound like him already. I’m hoping you can help me sort through his files.”

“Of course. How do you want them sorted?”

“You have to be exact about it. I don’t want class lectures mixed up with his research papers. These files look organized but they’re all confused. He tended to throw all sorts of things into the nearest file even if it didn’t belong there.”

I picked up one of the folders and leaned against the counter while I opened it. It contained several pages of graphs with the axes labeled wavelength and flux. They depicted the spectra of stars. There was some handwritten math in the margins, and I felt a little shock as I recognized Grandpa’s handwriting in the shapes of the numbers. He had held these pages just as I was holding them now.

“How do you know what pile this goes in?” I asked.

Joan pointed to the tab of the folder, which was labeled IRTF. “I think that’s for Infrared Telescope Facility. That’s in Hawaii. He did some observations there in the eighties. It goes in the research pile. You’ll have to look through everything in that folder, though. There may be some letters in there as well, and I don’t want those mixed in with the research notes.”

“What are you doing with all these papers once you’ve sorted them?”

“Something new,” Joan said. “You can take the files downstairs and sort them there.”

I looked up, and across from me the wall was covered with black-and-white photos. I recognized some of the people in them. “Is that Grandpa? And you?”

“Yes.”