Avi Loeb

“We know that [12.4-mile] asteroids are rare, because non-avian dinosaurs were killed by an asteroid half that size 66 million ago, whereas meter-scale asteroids impact the Earth every year,”

Avi Loeb · said date not stated · reported 2025-07-16

Avi Loeb noted the rarity of large asteroids hitting Earth compared to smaller ones.

“The simplest hypothesis is that 3I/ATLAS is a comet and we are missing the spectral features of its gaseous coma because of its large distance from Earth,”

Avi Loeb · said date not stated · reported 2025-07-16

Avi Loeb described the simplest explanation for the nature of 3I/ATLAS.

“The size anomaly of 3I/ATLAS will be easily clarified by upcoming data,”

Avi Loeb · said date not stated · reported 2025-07-16

Avi Loeb stated that future observations will help clarify questions regarding the size of 3I/ATLAS.

“gets closer to the Sun, it will get brighter. If it is a solid object without a cometary plume of gas or dust around it, then its brightness will increase inversely with the square of the decreasing distance from the Sun times the square of the distance from Earth.”

Avi Loeb · said date not stated · reported 2025-07-16

Avi Loeb explained how 3I/ATLAS's brightness will change as it approaches the Sun if it is a solid object.

“If 3I/ATLAS is not an asteroid — based on the interstellar reservoir argument in my paper, nor a comet — based on the lack of the spectral fingerprints of carbon-based molecules around it, then what is it?”

Avi Loeb · said date not stated · reported 2025-07-16

Avi Loeb questioned the classification of 3I/ATLAS if it proves to be neither an asteroid nor a comet.

“size estimate makes little sense for an interstellar asteroid because the interstellar object 1I/’Oumuamua was 200 times smaller, and based on the statistics of asteroids in the Solar system, we should have discovered a million objects of the scale of 1I/’Oumuamua before spotting one interstellar object that is [roughly 12.4 miles] in diameter,”

Avi Loeb · said date not stated · reported 2025-07-16

Avi Loeb explained why the estimated size of 3I/ATLAS makes it unusual compared to previous interstellar objects.

“sent towards the inner solar system by design”

Avi Loeb · said date not stated · reported 2025-07-16

Avi Loeb discussed the possibility that the newly discovered interstellar object 3I/ATLAS might have artificial origins.

“Let us instead maintain our childhood curiosity and seek evidence rather than pretend to be the adults in the room that know the answers in advance,”

Avi Loeb · said date not stated · reported 2025-07-16

Avi Loeb urged scientists to keep an open mind and seek evidence regarding interstellar phenomena.