We got the aliens' first message when they were nine years out, about the distance of Neptune. It was a series of microwave pulses repeating the prime numbers between 1 and 1000 every few minutes. We replied with different sequences—squares, cubes, Fibonacci’s—until they were matched in reply and the back-and-forth was steady.

We then worked out a common language. I won’t bore you with details, except to say it was the most electrifying experience of my life. Mathematicians are not often considered sentimental, but recalling the sheer awe of the enterprise, its elegant precision, can still bring me close to tears.

Within a few months, we could communicate on technical matters. By the following year, it was downright conversational. They wanted quartz granules. Sand. Their vessel and instrumentation was based on crystalline silicates, and they’d spotted the Sahara from God-knows-how-many light years out. They asked for about a billion cubic feet, roughly a hundred pyramids worth, and offered to barter.

The ensuing global brouhaha is well-documented, though I doubt anyone who didn’t live through it can appreciate the scope of the madness. Social, political, religious, scientific, nationalistic, psychological: every possible human reaction played out. There were conflicts and deaths, alliances formed or dissolved. Once the panic more or less settled, we still had six years to wait before their arrival. That was when I was most anxious: wondering what else we’d do to embarrass ourselves.

After they settled into orbit, they began sending shuttles to scoop up a few tons of sand at a time. Over and over, around the clock, for nearly a year. They explained, with courteous regret, that they were unable to leave their craft or host visitors so any face-to-face meeting (they adopted our colloquialisms, since we proved incapable of grasping theirs) would be impossible.

Again, we behaved badly. Arguments and posturing. A few overt aggressions. At least one of their shuttles was shot down. They accepted our apology. A sect of lunatic zealots launched an improvised missile at them, which made it about four miles into the air before plummeting impotently in the ocean. They pretended not to notice.

After nine months, they had all they needed. They thanked the Planet Earth, sent us in return specifications for vastly improved battery technology (that’s why you only have to charge your phone two or three times a year now… it used to be every day, if you can believe it), and left. That was almost forty years ago. Astronomers still track them, gently accelerating away with propulsion we don’t understand toward destinations they declined to specify.

When I was twelve, standing at a post office counter, a handsome man asked to borrow my pen. I handed it over without a word. He signed a few things, smiled and handed it back. Through the window I watched him get into an expensive car with a beautiful woman and drive away. For years, I dreamed about their journeys. Never once was I silly enough to hope they thought of me.

A few years ago, in a pit of drunken depression, I composed a poem for the aliens using the exquisite quaternary dialect they taught us to speak. I even beamed it off. I’m still waiting to hear back.

A generation has now grown up in a world where aliens exist. Oh, there’s still conspiracy theorists that cry hoax, and fanatics who preach about angels or demons, but most of us have come to accept the brutal truth:

We are not alone.

We are just unwelcome.