NASA's ongoing watch: 3I/ATLAS comet leaves 15 'anomalies' as it exits Solar System
Enigmatic object has captivated astronomers, sparked intense debate in scientific circles
As of December 19, 2025, the interstellar visitor known as 3I/ATLAS (officially designated C/2025 N1) is making its closest approach to Earth before continuing its journey out of our Solar System.
This enigmatic object, about 270 million km from Earth at its closest pass today, is the third confirmed interstellar comet to visit our neighbourhood.
For context the Sun is about150 million km from Earth. Yet 3I/ATLAS has captivated astronomers and sparked intense debate within the scientific community.
NASA's latest update highlights continued observations (which can be tracked only with the help of an 20cm telescope or larger), while Harvard astrophysicist Avi Loeb has pointed to a series of anomalies that challenge conventional explanations for its behavior.
Cosmic wanderer from beyond
Discovered in early 2025 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) survey, 3I/ATLAS hails from outside our solar system, much like its predecessors 'Oumuamua (1I/2017 U1) and 2I/Borisov.
Unlike typical comets that orbit the Sun in elongated paths within the Oort Cloud, interstellar objects like 3I/ATLAS are unbound to our star, travelling on hyperbolic trajectories that carry them in from distant stellar systems and back out into the void.
Also Read: 3I/ATLAS: December 19 is closest approach
Orbital diagrams show 3I/ATLAS swinging through the inner solar system, passing close to Jupiter, Mars, Earth, Venus, and the Sun before its outbound leg.
A visualisation of its path reveals a retrograde orbit — moving opposite to the direction of most planets — tilted nearly perpendicular to the "ecliptic plane", the flat disk where Earth and its siblings revolve around the Sun.
This unusual alignment has allowed it to skim by multiple planets without a dangerously close encounter with Earth, maintaining a safe distance during today's periapsis.
NASA's post on X from December 18 emphasises their vigilant monitoring: "We're continuing to observe the interstellar comet 3I/ATLAS as it heads out of our solar system."
15 anomalies
While NASA maintains a focus on standard astronomical analysis, Harvard's Avi Loeb — a vocal proponent of considering extraterrestrial technology in unexplained phenomena — has compiled a list of 15 peculiarities that set 3I/ATLAS apart from typical comets.
These anomalies suggest the object may not fit neatly into natural categories:
Jet pointing toward the Sun, not away from it: Unlike comets that eject material away from solar heat, 3I/ATLAS's jet directs inward.
Tightly collimated jet: The ejection is unusually focused, like a narrow beam rather than a diffuse spray.
Stable jet direction over time: It maintains consistency, defying expectations of variability.
Retrograde orbit: Travelling counter to planetary motion, increasing the odds of gravitational interactions.
Orbit nearly opposite to the ecliptic plane: Highly inclined, making its path through the system atypical.
Close flybys of multiple planets: It has grazed Jupiter, Mars, Venus, and others without disruption.
Avoids a close pass with Earth: Despite proximity, it steers clear of hazardous distances.
No clear dust coma: Lacking the hazy envelope of dust and gas common in active comets.
Unusual brightness behaviour: Fluctuations in luminosity don't match standard models.
Activity at distances where comets are usually inactive: Outbursts occur far from the Sun, where ice shouldn't sublimate.
Abnormal response to solar heating: Reactions to warmth deviate from predicted patterns.
Nickel detected without iron: Spectral analysis shows nickel but no accompanying iron, an odd composition.
Lack of expected carbon-based volatiles: Missing common organic compounds found in comets.
Jet behaviour not explained by water-ice sublimation: Traditional mechanisms don't account for the jets.
All anomalies appearing together: The sheer accumulation is statistically rare for a natural body.
Loeb argues that this confluence of oddities warrants scrutiny beyond conventional comet theories, echoing his earlier hypotheses about 'Oumuamua potentially being an artificial probe.
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