3I/ATLAS defies easy answers as Avi Loeb sticks with rank 4 assessment

The Morning Edition reports on new statements by Harvard astrophysicist Avi Loeb regarding the interstellar object known as 3I/ATLAS.

Loeb has decided to keep the object at rank 4 on his Loeb Classification Scale, a system he designed to assess whether interstellar objects may have an artificial origin.

The scale ranges from 0, meaning a natural object such as an icy rock, to 10, meaning confirmed alien technology.

In a recent article published on Medium, Loeb explained that while 3I/ATLAS shows several unusual features, the available data do not support changing its classification at this time.

He wrote that the object is “most likely a comet of natural origin,” despite a number of unresolved observations.

The ranking reflects uncertainty rather than a claim of non-natural origin.

3I/ATLAS has drawn attention because it is only the third known interstellar object detected passing through the solar system.

Observations have revealed unusual gas activity and a rare jet structure pointing toward the Sun.

These features have led to public discussion, but Loeb has emphasised the need for restraint until more evidence is collected.

Scientists are now focused on the object’s upcoming close approach to Jupiter in March 2026. That encounter may provide new data that could clarify the nature of 3I/ATLAS and allow its classification to be updated.

What does rank 4 mean on the Loeb scale for 3I/ATLAS?

Rank 4 on the Loeb Classification Scale refers to objects that show anomalies that are not fully explained but are still more consistent with natural causes than artificial ones.

According to Loeb, this category is designed to acknowledge open questions without making unsupported claims.

In his article, he stated that “natural explanations are prevalent but cannot fully explain the observed behaviour.”

Loeb identified a total of 15 anomalies associated with 3I/ATLAS, though he noted that only eight are significant enough to affect its ranking. One of the most discussed features is an anti-tail jet that appears to point toward the Sun.

Loeb described it as “the longest anti-tail jet ever observed,” with an estimated length of nearly one million kilometres.

Another observation involves the direction of the jet, which appears to align closely with the ecliptic plane. This alignment has raised questions about whether standard comet models can fully account for the object’s behaviour.

However, Loeb cautioned against drawing conclusions too quickly. He wrote that “speculation should be supported by evidence rather than guesswork.”

The rank 4 designation is meant to remain flexible. As new observations are made, the ranking can move up or down. Until then, the current classification reflects uncertainty rather than confirmation of any non-natural origin.

Jupiter flyby and next steps for scientists 

The next major opportunity to study 3I/ATLAS will occur during its closest approach to Jupiter on 16 March 2026. The object is expected to pass within about 53.5 million kilometres of the planet. At that distance, Jupiter’s gravitational influence will be stronger than the Sun’s tidal force acting on the object.

Researchers expect this flyby to allow improved imaging and spectroscopic measurements. These observations could help determine the object’s composition, structure, and gas activity in greater detail.

Loeb has stated that the ranking should not change until such data are available. He emphasised that “it is necessary to wait and not revise the ranking until new information comes in.”

The Loeb Classification Scale was designed to provide a structured way to evaluate claims about interstellar objects. Loeb has said the goal is to ensure that “extraordinary claims are accompanied by extraordinary evidence.”

The scale has previously been applied to other objects, including ’Oumuamua.

Public interest in 3I/ATLAS remains high, but Loeb has continued to stress caution. He has argued that interstellar archaeology should rely on verified measurements rather than assumptions.

Until the Jupiter encounter provides new results, 3I/ATLAS will remain at rank 4.
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