by Avi Loeb
Only once it was past us did astronomers on Earth glimpse our departing guest. We assigned the object several official designations, finally landing on one: 1I/2017 U1. But our planet’s scientific community and the public would come to know it simply as ‘Oumuamua—a Hawaiian name reflecting the geographical location of the telescope used to discover the object.
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The islands of Hawaii are jewels in the Pacific Ocean that attract tourists from around the world. But to astronomers, they hold an additional allure: they are home to some of the planet’s most sophisticated telescopes, a testament to our most advanced technologies.
Among Hawaii’s state-of-the-art telescopes are the ones that make up the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), a network of telescopes and high-definition cameras located at an observatory atop Haleakala, the dormant volcano that forms most of the island of Maui. One of the telescopes, Pan-STARRS1, has the highest-definition camera on the planet, and since it came online, the system overall has discovered most of the near-Earth comets and asteroids found in the solar system. But Pan-STARRS has another distinction—it gathered the data that initially tipped us off to ‘Oumuamua’s existence.
On October 19, astronomer Robert Weryk at the Haleakala Observatory discovered ‘Oumuamua in the data collected by the Pan-STARRS telescope, images that showed the object as a point of light speeding across the sky, moving too quickly to be bound by the Sun’s gravity. This clue quickly led the astronomy community to agree that Weryk had found the first interstellar object ever detected in our solar system. Yet by the time we had come up with a name for the object, it was over twenty million miles from Earth, or approximately eighty-five times as distant as the Moon, and rapidly moving away from us.
Combined telescope image of the first interstellar object, ‘Oumuamua, circled, as an unresolved point source at the center. It is surrounded by the trails of faint stars, each smeared into a series of dots as the telescope snapshots tracked the moving ‘Oumuamua.
ESO/K. Meech et al.
It came into our neighborhood a stranger, but it departed as something more. The object to which we had given a name had left us with a host of unanswered questions that would fully engage scientists’ scrutiny as well as the world’s imagination.
The Hawaiian word ‘oumuamua (pronounced “oh moo ah moo ah”) is loosely translated as “scout.” In its announcement of the object’s official designation, the International Astronomical Union defined ‘oumuamua slightly differently, as “a messenger from afar arriving first.” Either way, the name clearly implies that the object was the first of others to come.
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Eventually, the media called ‘Oumuamua “weird,” “mysterious,” and “strange.” But compared to what? The answer, in brief, is that this scout was weird and mysterious and strange when compared to all other comets and asteroids previously discovered, ever.
In fact, scientists could not state with certainty whether this scout even was a comet or an asteroid.
It’s not as if we didn’t have a basis for comparison. Thousands of asteroids, dry rocks hurtling through space, are discovered every year, and the number of icy comets in our solar system is greater than our instruments can count.
Interstellar visitors are far rarer than asteroids or comets. In fact, at the time of ‘Oumuamua’s discovery, we had never seen an object that originated outside of our solar system pass through it.
This distinction was quickly lost. A second interstellar object was discovered shortly after ‘Oumuamua was identified, and in the future, we are likely to discover many more, particularly with the Vera C. Rubin Observatory’s upcoming Legacy Survey of Space and Time (LSST). And in a way, we had come to expect these visitors even before we could see them. Statistics suggest that while the population of interstellar objects crossing Earth’s orbital plane is magnitudes smaller than the population of objects originating within the solar system, they are not themselves unusual. In short, the idea that our solar system sometimes plays host to rare interstellar objects is wondrous, but there is no mystery to it. And at first, the plainer facts of ‘Oumuamua promised only wonder. Soon after ‘Oumuamua’s discovery was announced by the Institute for Astronomy at the University of Hawaii, on October 26, 2017, scientists around the world reviewed the most rudimentary data collected and agreed on most of the basic facts: ‘Oumuamua’s trajectory, its speed, and its approximate size (it was under one-quarter of a mile in diameter). None of these early details suggested that ‘Oumuamua was unusual for any reason other than its origin outside our star system.
But before long, scientists sifting through the accumulating data began to point out ‘Oumuamua’s peculiarities—details that soon made us question the assumption that this object was a run-of-the-mill, albeit interstellar, comet or asteroid. Indeed, mere weeks after the object’s discovery, in mid-November 2017, the International Astronomical Union—the organization that names newly identified objects in space—changed its designation for ‘Oumuamua for the third and final time. Initially, the IAU had called it C/2017 U1; the C was for comet. Then it switched over to A/2017 U1; the A was for asteroid. Finally, the IAU declared it 1I/2017—the I stood for interstellar. By that point, that ‘Oumuamua had come from interstellar space was one of the few things upon which everyone agreed.
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A scientist must go where the evidence leads, the old adage runs. There is humility in following the evidence, and it frees you from preconceptions that can cloud observations and insight. Much the same can be said for adulthood, a good definition of which might be “the point at which you have gathered enough experience that your models have a high success rate in forecasting reality.” Not, perhaps, how you would present it to your young children, but still, I find the definition has its virtues.
In practice, this simply means that we should allow ourselves to stumble. Let go of prejudices. Wield William of Occam’s razor and seek the simplest explanation. Be willing to abandon models that fail, which some inevitably do when they collide with our imperfect grasp of facts and the laws of nature.
Obviously, there is life in the universe; we are testament to that. And that means that humanity provides a vast, compelling, sometimes inspiring, and sometimes sobering data set to consider when we wonder about the actions and intentions of any other intelligent life that might exist—or might have existed—in the universe. As the only example of sentient life that we have studied in depth, humans are very likely to hold many clues to the behavior of any other sentient life, past, present, or future, in the universe.
As a physicist, I am struck by the ubiquity of the physical laws that govern our own existence on our particular little planet. When I look out into the cosmos, I am awed by the order, by the fact that the laws of nature that we find here on Earth seem to apply out to the very edges of the universe. And for a long time, since well before the arrival of ‘Oumuamua, I have harbored a corollary thought: the ubiquity of these natural laws suggests that if there is intelligent life anywhere else, it will almost certainly include beings who recognize these ubiquitous laws and who are eager to go where the evidence leads, excited to theorize, gather data, test the theory, refine, and retest. And eventually, just as humankind has done, to explore.
Our civilization has sent five man-made objects into interstellar space: Voyager 1 and Voyager 2, Pioneer 10 and Pioneer 11, and New Horizons. This fact alone is suggestive of our unlimited potential to venture far out. So too is the behavior of our more distant ancestors. For millennia, humans have journeyed to the farthest reaches of our planet seeking different lives or better lives or just seeking, often with a shocking level of uncertainty about what they would find or whether they would return. Our species’ certainty increased substantially over time—astronauts managed to travel to the moon and back in 1969—but the fragility of these undertakings remains. It wasn’t the lunar module’s walls, which were about as thick as a sheet of paper, that kept the astronauts safe; it wa
s the science and engineering behind their construction.
And if other civilizations developed out there among the stars, wouldn’t they have felt that same urge to explore, to venture past familiar horizons in search of the new? Judging by human behavior, that would not be surprising in the least. Indeed, perhaps these beings grew so comfortable with the limitless expanse of space that they traveled in it in much the same way that, here on Earth, we now traverse the planet. Our forebears used terms like journeying and exploring; today, we go on vacations.
In July of 2017 my wife, Ofrit, our two daughters, Klil and Lotem, and I visited an impressive collection of telescopes in Hawaii. As the chair of the Department of Astronomy at Harvard University, I had been invited to give a lecture on Hawaii’s Big Island aimed at conveying the excitement of astronomy to the public, some of whom were protesting further construction of the next big telescope atop the dormant volcano Mauna Kea. I happily accepted and used the opportunity to visit some of the other Hawaiian islands, including Maui, that host state-of-the-art telescopes.
My subject was the habitability of the universe and the likelihood that in the coming decades, we would discover evidence of extraterrestrial life. And once we did, that discovery would force on humanity the appreciation that we’re not that special. The local paper’s headline covering my presentation nicely captured the idea: “Be Humble, Earthlings.”
The lecture was given a little less than a month before ‘Oumuamua—unbeknownst to Earthlings—passed the orbital plane of Mars, and I delivered it mere miles from Pan-STARRS1, one of the telescopes I visited on this trip and a technological marvel of instrumentation. Three months later, data gathered by Pan-STARRS would lead to the discovery of ‘Oumuamua.
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The first Pan-STARRS telescope, PS1, went online in 2008. Fifty years earlier, in 1958, another telescope had been built on the summit of Haleakala, but it was not used to study the stars; an animating fear at the time was Soviet satellites, and America wanted to be able to track them. Pan-STARRS, the Panoramic Survey Telescope and Rapid Response System, had a different objective: to detect comets and asteroids threatening to collide with Earth. As a consequence, since 2008 it has grown increasingly sophisticated. More telescopes have been added over the years, the most significant being Pan-STARRS2, which became fully operational in 2014. The array of telescopes collectively referred to as Pan-STARRS continue to map the skies above us, detecting comets, asteroids, exploding stars, and more.
In short, a bygone Cold War helped set in motion an observatory of such complexity and technological richness that, decades later, in the cold, clear atmosphere atop a dead volcano, a sophisticated instrument in the array was able to detect ‘Oumuamua, which passed overhead just a few years after this particular telescope opened for business.
It is easy to be impressed by the self-fulfilling quality of coincidences. But coincidences can be misleading. For much of human history, people have turned to mystical or religious explanations to make sense of occurrences that do not have clear causes. I like to think that even during our civilization’s youth and early adolescence, humankind was gathering enough experience that its models had an increasing success rate in forecasting reality. Humanity, you might say, has slowly been entering adulthood over the course of recorded time.
In truth, most events in life stem from a confluence of multiple causes. This is true in casual examples (eating the soup in the bowl that sits before you) and in extraordinary cases (the origins of, well, everything). These can run from the very personal (say, the introduction that leads to the marriage that produces two daughters keen to vacation in Hawaii) to the global (say, the possibility—the very real possibility—that for eleven days in October of that year, our telescopes witnessed an object that originated outside the solar system).
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My family and I returned from vacation to our century-old house outside of Boston, Massachusetts. It is in many respects vastly different from the farm in Israel where I was raised. But in the sense that it feeds my love of nature, my need to be in the midst of the things that grow and live among us, it is the same.
During an evening walk in the woods near my house, I witnessed a large tree falling in the forest that stretches out past our backyard. I first heard the cracks and then saw it give way and collapse. Its trunk, I saw, was hollow. Much of it had been dead for years, and on that date and at that time it could no longer hold up against the wind. It so happened I was there to see its demise—one part of a causal chain to which I was witness but over which I had no control.
But our actions can make a difference under more favorable circumstances. About a decade ago, when my family first moved to Lexington, I discovered a broken branch on a young tree in the yard. I was advised by a local gardener to cut off the nearly severed limb. On closer inspection, I saw that living fibers were still linking it to the rest of the tree. I chose to bind the branch together with insulation tape. Today the branch rises to the sky far above my head, but the insulation tape remains at eye level. That tree sits near the house, visible from our windows. I point it out to my daughters in order to remind them that humble acts can have extraordinary consequences.
Some of the most consequential decisions are made out of hopeful expectation of what might result. By the time I fixed the tree branch near my house, that was not only an article of faith for me but an oft-repeated experience.
2
The Farm
One of my earliest memories is of arriving a little late to school for my first day of first grade. When I walked into the classroom, the kids were running around and jumping on their chairs and even their desks. It was pandemonium.
My reaction was curiosity. I looked at my classmates and thought, Should I join them? Does it make sense to behave like this? Why are they doing this? Why would I? I stood by the door for a moment, trying to think my way through the questions.
The teacher came in a few seconds later. To say she was unhappy was an understatement. This was not how she wanted the new school year to begin. Attempting to assert her authority and calm down the students, she saw in me a chance to set things right. “Look at how well behaved Avi is,” she said to the class. “Can’t you all follow his example?”
But my placidity was not a sign of virtue. I hadn’t decided that the right thing to do was to stand quietly and await the teacher’s arrival; I just hadn’t figured out whether it would make sense for me to join in the mayhem.
I wanted to tell the teacher this but did not, which I now think was unfortunate. The lesson my classmates might have learned from my behavior—a lesson I eventually learned myself and that I have since tried to teach my own students—wasn’t about whether you should or shouldn’t follow the crowd but rather that you should take time to figure things out before acting.
In deliberation, there is the humility of uncertainty. This, too, is an attitude toward life that I have worked to embrace, cultivate in my students at Harvard, and instill in my daughters. After all, it is what my parents sought to instill in me.
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I grew up in Israel on our family’s farm in Beit Hanan, a village about fifteen miles south of Tel Aviv. It is an agricultural community dating back to 1929, and shortly after its founding it boasted 178 inhabitants. By 2018, however, that number had increased to only 548. When I was a child, the village was defined by its orchards and greenhouses, which grew all kinds of fruits, vegetables, and flowers. It was also a moshav, a special type of village. Unlike a kibbutz, where land is farmed communally, a moshav consists of individual families who own their own farms.
Our farm was notable for its large field of pecan trees—my father was head of Israel’s pecan industry—but we also grew oranges and grapefruit. When I was young, the pecan trees, which can grow to over one hundred feet, towered over me, but the citrus trees, with their distinctive, sharp odor when the fruit was ripe, rarely got above ten feet and were easier to climb.
Tending the groves and overseei
ng the necessary machinery was a full-time occupation for my father, David, who was a skilled problem solver. Indeed, I remember him most through objects: the tractors he maintained, the trees of our orchards he nursed, the appliances he mended throughout our home and farm. A particularly clear memory I have was his climbing atop the roof of our house in the summer of 1969 to ensure that the reception for our television would allow us to watch Apollo 11’s lunar landing.
No matter how able my father was, the sheer extent of work meant that there remained plenty of daily chores for my two sisters and me. We raised chickens, and at a very young age I collected eggs every afternoon and spent many nights with a flashlight hunting down fluffy chicks that had escaped from their cages.
Israel in the 1960s and 1970s, the decades of my earliest years, was a precarious place. After World War II, Jewish refugees increased the population by about a third, and the number of people in the region went from two million to just over three million. Many came from Europe, and the echoes of the Holocaust were never absent. What’s more, the Arab countries of the Middle East were resolutely hostile toward Israel, which was committed to holding its ground. One conflict followed another: the Sinai War of 1956 was followed by the Six-Day War of 1967, which was followed by the Yom Kippur War of 1973. Though only decades old at the time of my childhood, Israel was steeped in recent and ancient history, and Israelis then—as now—were aware that their nation’s continued survival depended on deliberating over the consequences of their choices.
It is also a beautiful country, and Beit Hanan and my family’s farm were splendid places to grow up in. This free atmosphere inspired my early writings, notes I collected and piled in the top drawer of my desk. Indeed, for much of my adulthood it was an animating faith for me that if my freethinking ways ever got me into trouble, I could always, and very happily, return to the farm of my childhood.