“Nothing.” Roger shook his head. “Don’t you think they should have found something by now?”
Ben leaned back in his chair and stretched. “I don’t know. I mean the thing is, just like we humans somehow imagine we’re separate from our environment, we also imagine that the solar system is separate from the interstellar environment, but it’s not.”
He pointed at the star field on Roger’s laptop. “Sedna, our tenth planetoid beyond Pluto, was captured when our solar system collided with another star system a billion years ago. Thirty-five million years ago, the Earth’s orbit changed, triggering a massive ice age and asteroid impacts that formed the Chesapeake Bay. I’d bet it was caused by another star passing through our solar system, just like Scholz’s star grazing us only seventy thousand years ago. ”
“Four million years ago, a star three times the size of the sun passed a half parsec from it.” Roger had obviously done some homework. “And a million years from now, a K7 dwarf will skim us at less than a tenth parsec.”
“Exactly,” Ben said. “We’re intimately connected to other stars around us in interstellar space. How many extinction-level events have there been in Earth’s history?”
Roger scrunched his face and smiled. It was one of his favorite topics. “Five big ones that wiped out more than half the life on Earth, plus dozens of smaller ones. Two hundred and fifty million years ago, the Permian extinction took out over ninety percent of life worldwide. It was tens of millions of years before the planet was inhabited by more than protozoa.”
“Caused by what?”
An almost rhetorical question, but Roger played along. “Asteroids, comets, and volcanoes...”
“But the real answer is, we don’t know. What about a star exploding, a supernova, within a few dozen light years?”
“That would do it,” Roger agreed. “Irradiate the Earth and kill nearly everything.”
“With no warning.”
“Nope. Can’t outrun the speed of light.”
Ben pointed at a new image on Roger’s screen. “In our galaxy there are billions of stars, bright points we can see, but there are hundreds of millions of neutron stars, collapsed remnants of stars, that float around between them and are almost invisible. That’s what we know, but it’s what we don’t know that I’m worried about.”
“And that is?”
“Dark matter. Ninety percent of the material that makes up our universe, that makes up our own galaxy, is made of something we can’t see. All those stars”—Ben stabbed a finger at the screen—“there’s ten times more stuff floating between them that we can’t see, but we know it’s there by its gravitational signature, by the way the galaxies hold together. Exactly the same way we know Nomad is there, that something is coming. We detect the effects of its gravity, but we can’t see anything.”
“So what are you saying?”
“That we don’t know. Who knows what wiped out life on Earth before? Maybe we’re about to have a cosmic encounter with something we don’t understand.” Ben hung his head. “I’ve always had the feeling we think we’re wizards.”
“You mean astronomers?” Roger’s face twitched into an expression halfway between a grimace and a grin. “Like we gaze into our crystal balls? It’s called scrying, I think.”
“Right. We stare at patterns of light, and imagine that we can divine the history of the universe, even predict the future. It’s pride, pure hubris. Five big extinction-level events, but maybe this one won’t just destroy life. Maybe it’ll actually destroy the planet.”
Roger turned his laptop off. “Do you think it’ll hit us?”
“Doesn’t need to. We can’t see it, but whatever it is, it has a massive gravitational field. The Earth is like a giant water balloon, the solid crust beneath our feet just the thin, stretched plastic surface. If this thing comes close enough, past the Roche limit, the Earth will burst from the tidal forces.”
“No matter what, it’ll fling the Earth into interstellar space,” Roger added quietly. “The atmosphere would freeze solid in a few weeks.”
“Let’s not get ahead of ourselves.” The connection symbol on Ben’s laptop winked on. He logged into his email. “We don’t know what it is; we have only a general sense of its path. Maybe it’ll miss the solar system. Maybe it will disappear.”
“Maybe.” But Roger didn’t sound convinced.
Ben scanned his inbox, flooded with media requests and colleagues requesting calls. But…there, an email from Jess, and not just one but a dozen. He opened the first one. “Oh, no…”
Roger blinked. “What?”
Ben read one email and then another. “Jess and Celeste didn’t get on that flight. They came to find me. Damn it.”
“Where are they?”
“I have an address. Go get Dr. Müller. I need him to arrange a pick-up in Rome. Arrange a military transport.”