On January 8, 2014, at 17:05:34 UT, an approximately meter-sized rock from space streaked through the sky off the coast of Manus Island, Papua New Guinea, burning up with an energy equivalent to about 110 metric tons of TNT and raining debris into the depths of the Pacific Ocean. Similar-sized fireballs are not uncommon occurrences in Earth’s skies; in fact, a few dozen of them occur each year. But what was unusual about this particular meteor was the very high speed and unusual direction at which it encountered our planet, which collectively suggested it came from interstellar space.
Sensors on a classified U.S. government satellite designed to detect foreign missile launches were the sole known witnesses to the fireball. Thanks to a partnership between the Department of Defense and NASA, the data describing the event eventually were shared on a public database hosted by the Center for Near Earth Object Studies (CNEOS) within the space agency’s Jet Propulsion Laboratory, along with data for more than 900 other fireballs recorded by U.S. government sensors between 1988 and present-day. The data for these events includes dates, times, latitudes, longitudes, altitudes, speeds, three-dimensional velocity components, and energies for each. Notably omitted from the database are the uncertainties for most of these measurements—presumably to ensure the precision thresholds for U.S. global sensing capabilities are not divulged, as this information could potentially be exploited by adversaries.
My involvement with this meteor traces back to April 2019, when my academic adviser at Harvard, astrophysicist Avi Loeb, brought the CNEOS fireballs catalogue to my attention. At the time, he and I were about eight months into our studies of data related to ‘Oumuamua, the object identified in October 2017 as the first known interstellar visitor to the solar system. Since ‘Oumuamua originated from outside of the solar system, each of its properties, including its very detection, conveyed previously inaccessible information about our cosmic neighborhood. With the wealth of knowledge carried by interstellar visitors foremost in our minds, Loeb and I had been pondering the possibility of finding others to study, and the CNEOS data seemed promising. Within days, I had identified the 2014 Manus Island fireball as a potential interstellar meteor candidate. Loeb then suggested that I use the speed of impact combined with knowledge of the kinematics of small-body populations in the solar system to estimate the probability that it originated from elsewhere, beyond our solar system. Contemplating this approach, I then proposed a more precise method to derive the object’s trajectory that accounted for the gravitational influences of our sun and its planets. Loeb agreed with my proposal and I swiftly got to work.
At Earth’s distance from the sun, any object moving faster than about 42 kilometers per second is in an unbounded, hyperbolic orbit relative to our star, meaning that it is too speedy to be captured by the sun’s gravity. Anything traveling over this local celestial speed limit, then, may come from (and if unimpeded should return to) interstellar space. The CNEOS entry for the 2014 Manus Island fireball indicated the meteor hit the Earth’s atmosphere at about 45 kilometers per second—very promising. However, some of this speed came from the object’s motion relative to the Earth and the Earth’s motion around the sun. Teasing apart these effects with the help of computer programs that I wrote, I found that the object had overtaken the Earth from behind before striking our atmosphere, and likely had a sun-relative speed closer to 60 kilometers per second. The corresponding orbit that I calculated was clearly unbound from the sun—even if there had been large uncertainty errors. If the data were correct, this event would be the first interstellar meteor ever discovered. And it was hiding in plain sight.
Extraordinary claims, of course, require extraordinary evidence. So Loeb and I reverse-engineered estimates of the classified satellites’ measurement errors, using independently verified data on other fireballs in the CNEOS database and elsewhere in the scientific literature. After this arduous reality check, we were left with the same astonishing conclusion: the 2014 fireball had clearly originated from interstellar space. In short order, we drafted a paper reporting our discovery for peer-reviewed publication.
Journal referees balked at the unknown nature of the error bars, so we enlisted the help of Alan Hurd and Matt Heavner, scientists at the Los Alamos National Laboratory with high-level security clearances as well as an interest in promoting collaboration with the public sector to enable blue-sky science. In short order, Heavner made contact with the anonymous analyst who had derived the meteor’s velocity components from the classified satellite observations, and who confirmed that the relevant uncertainties for each value were no higher than 10 percent. Plugged into our error analysis, this implied an interstellar origin with 99.999 percent certainty, but the paper was again turned down by referees, who raised objections about the fact that the statement about uncertainties was a private communication with an anonymous U.S. government employee, and not an official statement from the U.S. government, which Heavner had difficulty in procuring. After several further failed attempts to pierce the veil of secrecy to the satisfaction of journal reviewers, we regretfully moved on to other research, leaving the true nature of the 2014 meteor unconfirmed.
A year later, however, we were approached by Pete Worden, the chair of the Breakthrough Prize Foundation, with an introduction to Matt Daniels, who at the time was working for the Office of the Secretary of Defense. Daniels had read our preprint about the 2014 meteor and wished to help to confirm its origin from within the U.S. government. After a year of laboriously navigating multiple layers of government bureaucracy, in March/April 2022 Daniels was able to procure official confirmation from Lt. Gen. John Shaw, deputy commander of U.S. Space Force, and Joel Mozer, chief scientist of the branch’s Space Operations Command, of the relevant uncertainties—and thus effective confirmation that the meteor was of true interstellar origin.
Three years after our original discovery, the first object originating from outside of the solar system observed to strike the Earth—the first known interstellar meteor—has officially been recognized. The 2014 meteor is also the first recorded interstellar object to be detected in the solar system, predating ‘Oumuamua by over three years, and is one of three interstellar objects confirmed to date, alongside ‘Oumuamua and the interstellar comet Borisov.
The 2014 object’s interstellar nature carries fascinating consequences. Its size implies that each star needs to contribute a significant mass of similar objects over its lifetime to make the 2014 detection likely—suggesting there are many more interstellar meteors to be found. And its high speed relative to the average speeds of our neighboring stars suggests that it could have been ejected from deep within another planetary system, relatively close to its star. This is surprising, as one would naively expect most interstellar objects to instead originate from far more distant circumstellar regions where escape velocities are lower, namely the clouds of comets that exist at the outskirts of many star systems.
This new field, the study of interstellar meteors, certainly has much to tell us about our place in the cosmos. Further investigations of the observed properties of the 2014 meteor could reveal new insights about our local interstellar environment, especially when compared with the characteristics of its successors, ‘Oumuamua and Borisov. Meteor databases are ripe for follow-on searches, and fresh motivations exist for building new sensing networks, with a focus on detecting future interstellar meteors. Observing an interstellar meteor burn up in real time would allow for the study of its composition, yielding novel insights into the chemistry of other planetary systems.
The holy grail of interstellar object studies would be to obtain a physical sample of an object that originated from outside of the solar system—a goal as audacious as it is scientifically groundbreaking. We are currently investigating whether a mission to the bottom of the Pacific Ocean off the coast of Manus Island, in the hopes of finding fragments of the 2014 meteor, could be fruitful or even possible. Any sufficiently large interstellar meteor discovered in the future should also produce a shower of debris, which we could potentially track down and analyze. There is, of course, another approach for getting samples, which, as director of interstellar object studies for the Galileo Project, I am excited to also be pursuing: a spacecraft rendezvous. In collaboration with Alan Stern, the principal investigator of NASA’s New Horizons mission, we have now received funding to develop a concept for a space mission to some future interstellar object.
Like exotic seashells, these messengers from the stars have been washing ashore on our planetary beach for billions of years, each carrying secrets of their—and our—cosmic origins. Now, at last, we are starting to comb the shoreline.