Harvard Astrophysicist Avi Loeb Investigates Periodic Brightening in Comet 3I/ATLAS, Suggests Potential Technological Origin
Cambridge, MA – Harvard astrophysicist Avi Loeb is scrutinizing unusual periodic variations in the brightness of comet 3I/ATLAS, suggesting the observed “heartbeat-like” pulse could indicate a non-natural origin. loeb’s analysis, detailed in recent blog posts, centers on the comet’s jets – streams of gas and dust – and weather their activity is tied to the comet’s rotation or an external factor.
The inquiry stems from observations of 3I/ATLAS, an interstellar comet discovered in 2023. Initial analysis of Hubble space Telescope images taken on July 21, 2025, revealed that most of the comet’s observed light originates from a glowing halo, or coma, surrounding the nucleus. While the nucleus is visible through this obvious coma, determining the fraction of light reflected directly from the nucleus is challenging due to its unresolved size in the Hubble image.
Loeb initially questioned the connection between the observed variability and the comet’s ellipsoidal shape, stating in his blog, “the association of this variability with the ellipsoidal shape of the nucleus is not warranted.” He proposes a natural description involving sunward jets triggered by large pockets of ice on the nucleus facing the Sun. This woudl create a periodic “puff” of gas and dust, analogous to a heartbeat, with a cycle matching the comet’s 16.16-hour rotation period.
Though, Loeb also posits that a technological object could exhibit a pulsing jet pattern with an arbitrary direction, not necessarily aligned with the Sun. He notes a lack of systematic study in published literature regarding the orientation of this periodic brightening relative to the Sun.
“This heartbeat pattern should have been apparent in a series of well-calibrated snapshots of the coma over several days but none was systematically studied in the published literature,” Loeb wrote. He believes a movie showcasing the periodic brightening of the jets over several days could reveal whether the jets are natural or indicative of a technological source.
Loeb previously investigated 3I/ATLAS for non-gravitational acceleration, a phenomenon that can suggest forces beyond gravity are at play. Further updates on his findings are expected as more data becomes available.
