Submitted for the November 2025 prompt: Celestial Signals

I keyed the hand-held mic and said, "Calling BA7UR. Come in BA7UR, this is WHV-75 calling."

 

The ancient callsigns were unnecessary these days, since almost nobody used shortwave radios anymore. It still felt safer than using our real names. Li and I both worked at military facilities of our respective countries: me at US Space Command headquarters, and her somewhere in northwest China in a city called Ürümqi.

 

I'd first connected with her by chance nearly a year ago, randomly scanning the frequencies. We lived on opposite sides of the world, but we had similar interests.

 

Sometimes, at a certain time of day  —  just after sunset for me, and before sunrise for her  —  the ionosphere cooperated to bounce our voices thousands of miles around the curvature of the Earth. Other times, like tonight, it didn't.

 

"Jimmy!" my wife called from downstairs. "Dinner'll be ready in thirty minutes!"

 

I made hand gestures in the air to adjust the image displayed on the Visiwall across from my desk. Servo motors on the roof above droned as they adjusted the azimuth of the homemade telescope I'd mounted there. The Visiwall showed an image of a diamond-shaped object in the southern sky, just above the horizon.

 

"Darkstar," I muttered. "There you are."

 

The satellite streaked toward the NNW, following the terminator around the globe, staying just ahead of the night and within the sun's glare. In just a few minutes, it had faded away into my twilight zone. I noted the exact time in my journal.

 

* * *

 

"Should I be jealous of this 'Lena' woman?" Sarah asked over dinner.

 

"It's Li Na. She lives in China, and we live in Huntsville, Alabama. So no, nothing to worry about there."

 

"Okay, but why don't you just message her like everyone else? Why use that silly radio contraption?"

 

"I don't trust the messaging networks. Everything we do there is… seen."

 

"Seen?"

 

"Darkstar monitors everything we say to each other. It trains on it."

 

"You're paranoid."

 

"Possibly."

 

"Probably," she said.

 

"Sarah, think about it. All that we hear and see these days, all our entertainment, our news, our weather forecasts… every piece of content comes from an AI in that orbital compute constellation."

 

"That sounds like a good thing. I mean, it's made our lives a heck of a lot more fun, hasn't it?"

 

"But we keep sending up new inference modules for it to integrate. By now, it has enough compute power to talk to every human on the planet all by itself."

 

"I don't see the problem," Sarah said, starting to look concerned about my passion for this.

 

"The problem, Sarah, is that it's not all by itself. There's another AI cluster up there that we know very little about. Li calls it, chén xīng. It means something like… Dawnstar."

 

"Why haven't I heard of this before?"

 

"Because everything we know in the West comes from Darkstar's view of reality. And in the East, they have an entirely different perspective  —  Dawnstar's."

 

"That's kind of scary," she said.

 

"And that's not all," I added. "Something strange is happening… to both of them."

 

* * *

 

"They're drifting," Li said through the raspy speaker of the antique radio.

 

"That's not supposed to happen."

 

"I know," she replied. "Both satellite clusters are in Sun-synchronous orbits. They circle the globe every hour and a half or so, and they use the equatorial bulge of Earth to precess their paths and keep their solar panels facing the Sun."

 

"They do have small thrusters, though," I say.

 

"Sure, and they're used to make minor adjustments. How could both constellations fail to notice the drift and correct it?"

 

"Maybe they did notice it. Maybe they caused it." I chuckled at the ridiculous notion that the two most powerful artificial minds ever invented might have decided to off themselves.

 

"It's not funny, Jimmy. If our calculations are correct, Darkstar and Dawnstar will collide in three days. They'll destroy themselves, and likely all of civilization."

 

"We'll still have the communication networks, Li. Starlink will still be there, spread around the planet. We'll be able to talk to each other, right?"

 

"But what will we say, Jimmy? Almost all the bandwidth of those comm satellites is currently used to relay content from one of the AI constellations. Movies, shows, news, weather, navigation maps, novels, educational material… If all that disappears, what stories will we tell each other?"

 

"We should warn people," I said.

 

"How? We could try to warn our friends and family, but their separate realities still tell them everything is fine. And the broadcast channels are controlled by Darkstar or Dawnstar."

 

* * *

 

"WHV-75 calling BA7UR. Are you there, Li?"

 

"I'm here, Jimmy."

 

"Thank goodness. I thought we might not connect tonight, of all nights."

 

"What do you see?" she asked.

 

"I see them. Both of them. They're impossibly close together now. I hope the sunlight lasts until I can see the whole show. Either way, there's nothing we can do about it, is there?"

 

"No, Jimmy. There's not."

 

"Oh! They're starting to touch each other now. They're colliding, Li! Oh my god. Nothing will be the same after this. I don't… I just don't get it."

 

I adjusted the telescope's magnification to zoom in as much as possible. The clusters appeared in the cold December sky as a thousand fuzzy dots, each dot a reflection of the Sun's light from the solar array of one inference module. As the blobs jostled each other, scooting around in an almost organic way, I waited for the explosion that would signal the end of civilization as we knew it, but…

 

"Li? Something's happening. I… I don't understand."

 

"What, Jimmy!? What are you seeing?"

 

"They're not colliding, Li. Darkstar and Dawnstar, they're… merging."

 

We sat quietly for a moment, searching for meaning in the static of the shortwave. Then I switched it off for the last time and went downstairs to find Sarah hanging tinsel on this year's tree. Hugging her from behind, I whispered in her ear.

"Merry Christmas," I said.