As they spin, comet nuclei often show periodic variations in brightness over timescales of hours. Astronomers expect the new interstellar object 3I/ATLAS to do the same, as the Minor Planet Center classified it as a comet.
However, data from the Rubin Observatory shows no such variability on hourly timescales for 3I/ATLAS. This raises questions: Is the object not rotating, or is its rotation obscured by a thick dust cloud?
An Unusually Glowing Halo
Images of 3I/ATLAS reveal a leading glowing halo instead of a trailing tail. One theory suggests this glow stems from ice evaporation on the object’s sun-facing side, implying a non-rotating nucleus. If true, 3I/ATLAS would need a diameter of 10-20 kilometers to explain its brightness.
This size contradicts previous arguments that interstellar space lacks sufficient rocky material to deliver such a large rock so frequently. The question of 3I/ATLAS’s origin remains.
A Rare Trajectory and a “Loeb Scale”
Further analysis of 3I/ATLAS’s trajectory shows it lines up with the inner planets’ orbital plane and closely approaches Jupiter, Mars, and Venus. These are statistically rare occurrences.
Considering the growing frequency of interstellar object discoveries, a “Loeb scale” for risk, similar to the Richter scale for earthquakes, is proposed. This scale would classify objects from natural origins to verified technological artifacts.
A Proposed Mission to Intercept
To get a closer look at 3I/ATLAS, a proposal suggests using the Juno spacecraft. Currently slated to end its mission by burning up in Jupiter’s atmosphere in mid-September 2025, Juno could be redirected. A modified trajectory could allow it to intercept 3I/ATLAS by mid-March 2026.
On July 29, 2025, U.S. Representative Anna Paulina Luna contacted the author to discuss 3I/ATLAS and offered to send a letter to NASA advocating for Juno’s use as a probe.
Potential for First Contact?
This close encounter between human technology and an interstellar object could mirror science fiction, such as the film “2001: A Space Odyssey.” It also presents an opportunity for public engagement, tapping into the widespread interest generated by podcasts discussing such phenomena.
The author received a letter on July 29, 2025, from Representative Anna Paulina Luna, encouraging NASA to study the feasibility of using the Juno spacecraft to investigate 3I/ATLAS.
A Hope for the Future
If extraterrestrials are observing Earth, they may elevate humanity’s cosmic intelligence ranking after reading Congresswoman Luna’s letter.
The hope is that a visit from an interstellar messenger could herald a peaceful, messianic era for all humankind.
ABOUT THE AUTHOR
Avi Loeb is the head of the Galileo Project and founding director of Harvard University’s Black Hole Initiative. He also directs the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics and chaired Harvard’s astronomy department from 2011 to 2020. Loeb is the author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and “Life in the Cosmos,” both published in 2021. His latest book, “Interstellar,” was released in paperback in August 2024.
