The Galaxy That Should Not Hold Together

The crowd had left, and so had the warmth. Soren sat on the cold concrete floor of the observatory dome with his notebook on his knees, waiting for his dad to finish talking to a man about parking.

A laptop glowed on the equipment table. Next to it sat a coffee gone cold and a printout, slightly curled, with a galaxy on it.

The galaxy was a smudge. That was the first thing he noticed. Not a spiral, not a pinwheel like the posters by the door. Just a soft gray blur, like someone had breathed on a window and a few stars had gotten stuck in the fog.

Under it, a graduate student had written numbers in pencil. Soren read them twice.

He found the student by the telescope, coiling a cable around her elbow. Her name tag said Priya. She looked like she wanted to go home.

"Is this one real?" Soren asked, holding up the printout.

"Dragonfly forty-four. Very real. Annoyingly real." She kept coiling.

"Why annoyingly?"

She sighed, but it was a tired sigh, not a mean one. "Because it shouldn't be there. A galaxy that faint, with that few stars, should fall apart. The stars at the edges are moving too fast. Anything moving that fast should fling itself out into space and never come back."

Soren looked at the smudge again. "But it didn't."

"But it didn't."

He sat back down. This was the part of his brain that felt too small. He needed somewhere to put it.

He knew how a thing held together. You needed something pulling. He thought about swinging his backpack on its strap in a circle. The faster he swung it, the harder he had to grip. Let go, and it flew across the gym. The stars at the edge of Dragonfly forty-four were swinging fast. So something was gripping. Something with a very strong grip.

"So there must be a lot of stuff in it," Soren said. "Heavy stuff. To hold the fast stars."

Priya stopped coiling. "That's exactly the problem. Go on."

Soren stared at the smudge. He counted the visible stars in his head, the way he counted streetlights on the drive home. There weren't many. The galaxy was dim. Almost nothing was shining in it.

"But it's not heavy with stars," he said slowly. "There aren't enough stars. I can see there aren't enough. It's barely glowing."

"Right."

"So the heavy stuff doesn't glow."

Priya sat down on the floor across from him, which surprised him. Grown-ups doing science usually stayed standing.

"Here's the number," she said. "That galaxy is about as wide as our whole Milky Way. But it has maybe one out of every hundred of the stars. If you added up everything we can see in it, all the light, all the gas, all the dust, you'd get a tiny fraction of what's needed to keep it from flying apart."

"How tiny?"

"The part you can see is about one ten-thousandth of it."

Soren did the math he could do. "So the part nobody can see is the other nine thousand nine hundred and ninety-nine."

"Out of ten thousand. Yes."

He looked down at the printout, at the gentle gray nothing of it. He had thought he was looking at a dim galaxy. He understood now that he was looking at almost nothing at all. The smudge was the exception. The galaxy was the part of the picture that was blank.

"So where is it," he said. It wasn't quite a question.

"Everywhere in there. Around the stars. Between them. It's not hiding in a corner. It's the whole shape. The stars are just sprinkled into it, like." She searched for it. "Like a few sequins on an invisible dress."

Soren wrote the word sequins. Then he stopped writing.

"What is it made of?" he asked.

Priya was quiet for a second. "We don't know."

He looked up.

"I mean it," she said. "That's not me being lazy. Nobody on this planet knows. We've looked. We've built machines a kilometer underground to catch it. We've smashed particles together hoping to make some. We know it's there because of exactly what you just figured out, the fast stars and the strong grip. We can weigh it. We can map where it is. We just can't see it, can't touch it, can't catch it, can't say what it is."

"But it's most of the galaxy."

"It's most of every galaxy. It's most of the universe. The stuff you and I are made of, the stuff stars are made of, all of it together, that's the sequins. The dress is the part we can't name."

Soren sat with that. Outside the dome the real sky was wheeling slowly, full of points of light, and he had spent his whole life thinking those points were the universe. The lit-up parts. The parts that wanted to be seen.

They weren't the universe. They were the trim.

His dad's voice came from the doorway, asking if he was ready. Soren didn't answer right away.

"You figured out the shape of the problem faster than most of my students," Priya said, getting to her feet. "You weren't bothered that the answer is we don't know."

"I'm not bothered," Soren said. "It's the best part."

She almost laughed. "Why?"

He thought about how to say it. "Because somebody's going to find out. And right now nobody has. So it could be anybody." He looked at her. "It could be a person who's eleven."

Priya picked up her cold coffee and didn't drink it. "Keep the printout," she said. "I have another."

Soren walked out under the open part of the dome where the real sky showed through. He held the printout up at arm's length so the paper galaxy sat against the dark.

Then he moved the paper aside and looked at the black space where it had been, the part with no stars in it, and held very still.