Discovery of a Polar Interstellar Meteor (Polar-IM) from April 1, 2026
Following the rare meteor explosion over Boston at 2:06PM Eastern Time on May 30, 2026, I checked the database of NASA’s Center for Near-Earth Object Studies (CNEOS) (accessible here), which reports global bolide detections from U.S. Government sensors. Apparently, the Boston fireball released about 7% of the Hiroshima atomic bomb energy, equivalent to 1.1 kilotons of TNT. The bolide with a diameter of 1.6 meter — corresponding to a mass of order 6 metric tons - was traveling at a speed of a hundred times the speed of sound. Massive impactors of this scale occur once every couple of months over the entire Earth. The relic fragments from the meteoroid likely landed in Cape Cod Bay.
While looking at the CNEOS database, I noticed a recent meteor from 02:13:14 UTC on April 1, 2026, with a large polar velocity component relative to Earth of 59.8 kilometers per second, well above the local escape speed from the Solar System of 42.14 kilometers per second. Since the Earth’s poles are tilted by only 23.4 degrees relative to the orbital plane of the Earth around the Sun, the high polar speed of this meteor should not be corrected by much as a result of the motion of the Earth around the Sun, when transforming to the Sun’s frame. This led me to immediately conclude that the object is probably not bound by gravity to the Solar System and is interstellar in origin.
My inference was quickly confirmed by my brilliant postdoc Richard Cloete who already had the analysis formalism available from a previous paper that we wrote on interstellar meteors. Within a couple of days, Richard and I completed a new paper (available here), in which we identify this polar interstellar meteor, labeled Polar-IM, as the most robust interstellar meteor candidate ever reported in the CNEOS fireball database.
The fireball of Polar-IM was detected at latitude −41.9◦, longitude −54.7◦, and altitude 90.5 kilometers over the South Atlantic Ocean, east of Argentina. We transformed its reported Earth-fixed velocity vector (+3.6, −34.6, +59.8) kilometers per second to an inertial geocentric state, accounted for Earth’s gravitational acceleration with a two-body hyperbolic model, added the JPL Horizons heliocentric velocity of Earth, and tested the resulting heliocentric orbit against the solar escape speed. The final velocity component in the polar direction of +47.09 kilometers per second exceeded by itself the local solar escape speed. The full heliocentric speed of 51.73 kilometers per second, corresponding to a heliocentric excess speed of 30.00 kilometers per second, and an inclination angle of 89.4 degrees. We propagated measurement uncertainty through a million Monte-Carlo realizations using the empirical post-2018 low-discrepancy CNEOS error model (reported in a 2025 paper, accessible here). No realization yielded a bound heliocentric orbit, giving a statistical confidence on the interstellar origin of Polar-IM of more than 99.9997%. The Monte-Carlo statistical confidence corresponds to a 12.82-σ margin-to-scatter ratio under the adopted error model.
The telescopic discoveries of the interstellar objects 1I/`Oumuamua, 2I/Borisov, and 3I/ATLAS, demonstrated that large interstellar objects transit the inner Solar System. Population models predict many more meter-scale interstellar objects entering at rates potentially detectable with existing monitoring networks. Although these small bodies evade telescopic detection, they can reveal themselves as fireballs when they enter Earth’s atmosphere and generate a fireball as a result of their friction on air. The inferred velocity of Polar-IM is very reasonable for an interstellar origin.
Polar IM is the most robust interstellar meteor in the CNEOS catalog so far, as our analysis identifies its interstellar origin with a statistical confidence of over 99.9997%. The reported Polar-IM coordinates place the event over the South Atlantic Ocean, east of Argentina. The impact energy is modest, only 0.086 kiloton TNT equivalent, and the reported altitude is high, 90.5 kilometers. These two facts make material recovery less straightforward than in the impact site of a larger, lower-altitude bolide such as the 2014 interstellar meteor, IM1, where I led an ocean expedition in June 2023 that resulted in chemical analysis of recovered molten fragments (as reported here). The Polar-IM event may have fragmented high in the atmosphere, and any surviving material would require a fall-ellipse calculation before the feasibility of a search could be assessed. Given its impact energy and speed, Polar-IM had a mass of about 150 kilograms and a diameter of roughly half a meter.
The first follow-up priority is therefore a higher-fidelity reconstruction rather than an expedition, with a goal to: (1) produce targeted uncertainty-inflation and tail-sampling tests for the velocity errors required to cross the threshold for interstellar identification; (2) back-integrate the trajectory with a more detailed Earth-Moon-Sun model; (3) refine the inbound velocity vector; and (4) if warranted, model atmospheric entry, fragmentation, and wind drift to estimate a fall footprint. Independent validation is especially important because it is the main way to test a gross-outlier failure mode.
Any ground-based optical, infrasound, seismic, satellite, or regional fireball-network observation from 2026–04–01 at 02:13:14 UTC could help verify the velocity measurement of Polar-IM and test its interstellar origin.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, former 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.
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