Astrophysicist Avi Loeb, of Universidade of
Discovered on July 1, 2025 by the ATLAS system in Chile, the object travels at 61 km/s through Sistema Solar, with an origin outside it confirmed by its hyperbolic orbit.
Loeb argues that the brightness pattern, observed since July, is not only explained by the natural rotation of the nucleus, but by periodic jets of gas and dust in the coma.
NASA maintains the classification as a natural comet, based on spectral analyzes of images captured at Maryland, at Estados Unidos, at 2 pm local time on November 30, 2025.
Initial observations of the phenomenon
Ground-based telescopes have recorded brightness variations in 3I/ATLAS from July 2025, with a European and African study published in October in the journal Astronomy & Astrophysics.
The 16.16 hour cycle appears in calibrated light curves, but Loeb criticizes the lack of systematic sequences over days.
This initial data shows that less than 10% of the light comes from the nucleus, with the remainder from the coma, the surrounding gaseous envelope.
Jets and light modulations
The jets visible in the recent images, captured on November 16 and 17, 2025 at Novo México, at 8pm local time, exhibit varying directions, including anti-tails facing Sol.
Loeb compares the effect to a rhythmic flow, where masses of gas illuminate the coma cyclically.
In a November 2025 paper, he describes the pulse as independent of solar position in artificial scenarios.
The modulation occurs without strict alignment with the Sol, unlike typical ice sublimation processes.
These observations, from telescopes such as the Celestron EdgeHD 800, combine 60-second exposures to reveal collimated structures stretching millions of kilometers.
Hypotheses about the periodic cycle
European researchers attribute the cycle to the rotation of the nucleus, but Loeb rejects this on the basis of the nucleus’s minimal contribution to the total light.
- Pulses of 16.16 hours mainly affect coma, suggesting controlled ejections.
- Images from Hubble on July 21, 2025 show a dominant coma, with a core less than 2.8 km.
- Anomalies include non-gravitational acceleration, detected in NASA orbital data in October.
The pattern may arise from periodically heated pockets of ice, but Loeb emphasizes the rhythmic precision as atypical.
In analyzes from November 30, 2025, he proposes that jets function as impulses for trajectory adjustments.
Trajectory and planetary approaches
3I/ATLAS passed 29 million km from Marte in October 2025, at 8am local time at Pasadena, Califórnia.
Its route takes it within 170 million km of Terra on December 19, 2025, allowing for detailed observations with Hubble and Webb.
Loeb speculates that the approach to Júpiter in March 2026, 53 million km away, at 12:00 local time on Genebra, may involve releasing devices for data collection.
Data from the Juno probe, in orbit around Júpiter, will record particles from the jets on that date.
The retrograde orbit and residual accelerations defy purely gravitational models.
Position of the scientific community
NASA reaffirms the faint comet status of outer Sistema Solar, with OH emissions at frequencies of 1665 and 1667 MHz observed on November 14, 2025.
Studies on Astronomy and Physics from October 2025 conclude that the object exhibits typical characteristics, despite its interstellar origin.
Loeb advocates open analysis, citing “anomaly scaling” in his November 2025 blog.
Observatories like Mars Reconnaissance Orbiter captured views in October, confirming composition with C2 diatomic carbon.
Recent images and data
An image from November 30, 2025, processed by astronomers at Kalopa, at Havaí at 6am local time, reveals pulsating jets in asymmetric directions.
These captures combine 30-second exposures, highlighting luminous nodules in the anticola.
The green glow observed in September 2025 indicates active chemical activity.
Loeb notes that the lack of post-perihelion disintegration, on October 28, 2025, reinforces unnatural hypotheses.
Details of radio emissions
Narrow absorption signals at 1665 MHz were detected on November 14, 2025, coinciding with peaks in aerodynamic stress.
These frequencies, associated with hydrogen and hydroxyl emissions, show non-chaotic periodicity.
Analysis of Loeb links the signals to jet pulses, suggesting intentional environmental modulation.
Data from Earth-based satellites, limited by distance, do not capture particles directly, but corroborate the rhythm.
The phenomenon differs from broad thermal noise in natural comets.
Preparations for future observations
Telescopes on the ground and in space prepare sequences to monitor the pulse in December 2025.
ESA’s Juice probe will contribute data during its passage through Júpiter.
Loeb recommends daily calibrated images to verify alignment with the Sol.
These efforts aim to differentiate natural from technological causes in the coming months.
The proximity to Terra on December 19, 2025 provides a unique window for detailed spectroscopy.