The Scientific Revolution of Interstellar Objects
Recently, I was invited to attend a NASCAR car race on October 25, 2025 in Bakersfield, California, where one of the racers, Alex Malycke, will decorate the hood of his car with images of me and the interstellar object 3I/ATLAS. I told Alex that this honor is more meaningful for me than to the interstellar object because 3I/ATLAS is currently moving at a speed of 68 kilometers per second behind the Sun — at least 600 times faster than his car.
Around the same time, I was invited to a podcast interview with Joe Rogan, where I will break some interesting news.
Yesterday, 51 stippled watercolors featuring pioneers of science were placed on the walls of my Harvard office along with two bronze sculptures of Galileo Galilei — who demonstrated that the Moons of Jupiter do not revolve around the Earth, all donated by the remarkable artist, Greg Wyatt. While the carpenter was hanging Greg’s framed watercolors behind me, New-York Mayor, Eric Adams, and his staff held a zoom meeting with me to discuss my latest research. An hour later, I had a zoom meeting with the wonderful Jane Rosenthal, co-founder, CEO and executive chair of Tribeca Enterprises. Our conversation was followed by a podcast interview from India about interstellar objects.
What is all the fuss about?
We are living through a new revolution in astronomy, which traditional astronomers are slow to appreciate. Interstellar objects are transformative because astronomy was traditionally focused on remote observing of distant objects without the ability to retrieve materials from them because of the vast expanse of cosmic space (measured in billions of light years) and time (measured in billions of years). Astronomers had direct access to gas and dust particles from the immediate interstellar environment of the Solar system, but not to massive objects from much farther away. The discovery of interstellar objects over the past decade opens a new opportunity for laboratory studies of materials that originated from the vast cosmic scales we could only observe remotely before.
This new frontier could revolutionize astronomy, astrobiology and space exploration, in six ways:
· Constituting a census of the abundance of interstellar objects as a function of size and composition can inform us about their most prolific formation sites.
· Enabling laboratory studies of sample return from interstellar objects which hold the promise of providing evidence for the building blocks of life near other stars, in the spirit of the OSIRIS-REx mission to the Solar system asteroid Bennu (as described here and here). This opportunity constitutes a new frontier of astrobiology which complements the traditional search for the molecular fingerprints of microbes in the atmosphere of exoplanets. The latter search was singled out as the highest priority in the Decadal Survey on Astronomy and Astrophysics 2020, worthy of investing more than 10 billion dollars over the next two decades.
· Discovering technological relics could inform humanity of activities of other intelligent civilizations, ranked high on the Loeb Scale (as quantified here and here). This is a topic of great interest to the public and holds a great potential for education about evidence-based science and for inspiring children to become scientists.
· Motivating the construction of a copy of the NSF-DOE Rubin Observatory for the Northern sky, to complement Rubin’s Legacy Survey of Space and Time (LSST) which currently covers the Southern sky.
· Discovering invisible interstellar objects that do not reflect sunlight or that move too fast to be recognized in current sky surveys. Dark or fast interstellar objects could potentially be discovered by gravitational wave detectors if they are sufficiently massive (as discussed here and here).
· Identifying a potential threat from alien technology. This could motivate the deployment of a fleet of space telescopes and interceptors in the outer solar system as an alert system for Earth. The huge financial implications from the first encounter with alien technology might justify an annual investment at a level of a trillion dollars, as a sizable fraction of the global military budget worldwide. In the long run, the realization that we are not alone could inspire interstellar travel projects for humanity.
The anomalies of the first interstellar object 1I/`Oumuamua (as reviewed here) were realized too late to collect sufficient data that reveal its nature. After there was no evidence for gas or dust around it, its initial definition as a comet was changed to that of an asteroid. But after its non-gravitational acceleration was measured, comet experts labeled it as a `dark comet’, namely a comet with an invisible tail despite the requirement for it to lose as much as 10% of its mass in order to exhibit the observed non-gravitational acceleration. The second interstellar object 2I/Borisov violated the proposal that interstellar cometary tails are dark since it displayed a familiar bright tail.
Additional puzzles were raised in 2025 through the discovery of 3I/ATLAS, which displays 8 new anomalies (summarized most recently here). The large size and orbital alignment of 3I/ATLAS offer a unique opportunity to study it with ground-based and space-based observatories, but the lack of prior planning did not allow for an intercept mission. As the Rubin Observatory finds new interstellar objects, the time will be ripe for intercept and rendezvous missions that might involve sample returns from future anomalous objects like 1I/`Oumuamua or 3I/ATLAS.
Studying interstellar objects up close is a new way for exploring the unknown beyond the boundaries of the solar system. These visitors to our back yard hold the potential for revolutionizing the perception of our place in the Universe, and inspiring our most ambitious projects for space exploration.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
