I remember the day I decided I was going to be an xenoanthropologist–it was in the first grade, when our teacher showed us the now-famous images from the HAROA telescopes. That was just after they’d commissioned the telescopes in Houston and Denver, and they were pointing the array at planets they’d already confirmed using smaller-baseline arrays. I remember my teacher trying to explain how it worked–that with math you could use small telescopes spread over a long distance as one big one, a principle called interferometry we could barely pronounce–but my classmates and I were more struck by what those famous first images of Gliese 667 Cc showed. Back when my parents were kids, they’d used the dimming of its parent star to speculate there was a planet there, and the first generation optical interferometers–ones with baselines measured in a few tens of kilometers–had been enough to actually resolve the planet and confirm it existed. But that image was the first time we had enough resolution to really see it as a planet–blurry, pixelated oceans, continents, icecaps. And there, on the nightside of the terminator….scattered points of dim light. It took me years in school to realize what that moment meant to me, but that’s the day I knew humans weren’t alone in the universe, and that I wanted to study those lights.
The old sci-fi books I devoured as a kid had all assumed that our contact with aliens would start with a meeting or a message: we would go to their world or they would come to ours, or we would pick up each other’s radio signals and start talking back and forth. Instead we had found them, and they probably didn’t know we existed. In fact, it took years to even know they existed. We already had spectroscopy data that showed elevated oxygen levels in their atmosphere–proof of ongoing chemical processes for replacing it, but for all scientists could initially say with those first famous photographs, we were just looking at vast colonies of photosynthetic, bioluminescent algae. It wasn’t until years had gone by, and I’d spent all of high school digging into physics, math, biology, and history, that they finally commissioned a telescope array capable of seeing smaller geographic features–tens of kilometers instead of hundreds. The articles I read on Popular Science’s site explained how scientists were charting the positions of the lights through time, cross-comparing to oceans, bays, mountains, and rivers we could infer only from the green lines they cut through deserts, and the spectral analysis of the lights themselves–finally showing proof that those points of light were the product of campfires and lamps, not just glowing moss.
In a way, that was the entire discipline of xenoanthropology: poring over the latest images from the best telescopes, seeing what could be implied, inferred, or just guessed. We watched the points of light grow, new ones sprout on other continents–were we watching another race’s Age of Exploration? People wrote entire papers on the implications of the ways those dots of light and faint daylight blobs moved and grew for their transportation, their culture, and their politics. I was one of those people, in my undergrad years and my early grad work–we were the modern day Schiaparelli, seeing canals on Mars. I look back on those papers….what we didn’t know! But it was enough to keep the interest of some of the public, the part that hadn’t gotten bored when it turned out the aliens weren’t beaming out new episodes of Kitchen Gladiators or immediately retreated into endless circular discussions of the theological implications here on Earth. But that was the best we could see with a telescope array limited by the diameter of the Earth: ten kilometers of resolution. Anything smaller than a town, and we couldn’t even see it.
I was a postdoc at the HAROA central station in Boulder when we finally got the approval for the space-based optical telescopes, the Lightsecond Array. One at Earth-Moon Lagrange Four, the other at Lagrange Five, the two telescopes were massive things, fine webs of stretched-mylar mirrors miles across. Technically, it wasn’t a lightsecond, it was 2.22 lightseconds, almost bang on 666,000 kilometers of separation squinting down the line to Gliese. When we could steal time on what we around the lab called the Lucifer Array from the plain old astronomers staring at exoplanets that didn’t sport their own branch of the tree of life, we could finally see everything. It was a little uncomfortable, actually: the unblinking Eye of Sauron peering down with a resolution of 183 meters. The press releases had described us as being able to “see a soccer stadium,” but more to the point we could see…well, whatever they called it, the game they played on the grass fields in the center of their towns and cities. With Lucifer, we could see the ships we’d speculated must exist–sail-powered, just like we’d thought. I remember the first time the lights of a ship we were tracking didn’t reappear after a major storm–the first time I looked at Gliese and knew I’d just seen hundreds of deaths that these 1700s-era people could never solve. It almost felt voyeuristic, as we catalogued wars and weather and settlers on the frontier. But I was hooked, just like I’d been in Ms. Mueller’s classroom thirty years ago.
I remember even more as we saw those lights increasing in number, the increased levels of carbon dioxide and other products in their atmosphere around their largest cities–we’d started watching about the time they’d started their first Industrial Revolution, the one powered by water, but by the way the cities started moving away from rivers and the smoke and light of their furnaces we could tell when they entered the Age of Steam. With that came new craftsmanship on their part, and we made our own improvements–new telescopes spread further from Earth, giving us the resolution to see buildings, streets, the details of their ships and trains, and more. Others wrote a dozen papers speculating on it, but I just remember shouting for my wife who’d gone to get us coffee from the breakroom when Denver got the latest round of images from one of their major ports. They’d started building some kind of statue on an island–of course, I always call her Lady Liberty. But she was hundreds of meters tall, and with that we finally knew what they looked like, all four arms and six legs of them, like spider-centaurs.
With all the developments we saw them making as I rose up the ladder of the observatory staff, my worst nightmare was always that they’d have their Black Plague, their nuclear moment: that one day I’d see entire cities flicker and burn and go out like that ship in the storm–an entire species dying out or killing itself while we couldn’t do anything but watch. That’s why we’ve been doing it–they’re developing electricity these days, we’ve seen the change in their lights, the dams on their rivers for hydro power. Someday soon, they’ll finally invent the radio, and they’ll get the signals my team has been sending out–math and encoded pictures, greetings from Earth to tell them they’re not alone. It could be lost in the interstellar static, I don’t know how long it will take for them to hear it, or to build an antenna capable of replying but…I’d like to see it happen before I’m back out of the picture.
…What is it, Sam? I’m bus…what? Show me!
I’m looking at another picture now, just off the Array. We didn’t need the resolution for it, not in the end. And we didn’t need the radio telescopes we’ve had listening for the first faint flickers of any reply among the background hum of the universe. You were smarter than that, and I should have known. We told you we were watching, and when you heard, you just wanted to show you’d heard. The image Sam’s got pulled up on her tablet is that same globe I’ve seen for decades–the one I know almost better than a map of Earth or the lunar colonies. I know every point of light, every city and town. The coordination you’re showing us! She hits play again, and it happens: across an entire seacoast, over the course of hours, the lights in a dozen cities and towns flicker off, then on, then off. An hour passes, then off and on again twice more, then another hour of darkness, then three more flashes. You get to eleven before the lights finally come back on steadily, then fade out in the familiar ways before the coming dawn. Primes, aimed right back along our radio beam. It’s amazing. I’ve spent my whole career watching you, moments of insight and wonder at the light flashing across lightyears. But I don’t think I’ll ever forget this moment–the moment you knew we were looking and you took the chance to talk back.