Avi Loeb estimates ten trillion interstellar objects like 3I/ATLAS in the Solar System

Astronomer Avi Loeb, from Universidade of Harvard, has presented an estimate that redefines understanding of the population of interstellar objects in Sistema Solar. Baseado in recent observations of comet 3I/ATLAS, he calculates the existence of approximately ten trillion similar bodies within the boundaries of Nuvem and Oort. Essa analysis arises from data collected by Telescópio Espacial Hubble and the ATLAS monitoring system.

Comet 3I/ATLAS was discovered on July 1, 2025 by Asteroid Terrestrial-impact Last Alert System, known as ATLAS. Trata is the third confirmed object of interstellar origin to pass through Sistema Solar, after 1I/’Oumuamua, in 2017, and 2I/Borisov, in 2019. Sua hyperbolic trajectory confirms that it is not gravitationally bound to Sol.

Observations indicate that the nucleus of 3I/ATLAS has a radius of about 1.3 kilometers. With an average density of 0.5 grams per cubic centimeter, typical of comets, its mass totals approximately 5 billion tons. Esses parameters serve as the basis for projections of Loeb over a larger population.

Discovery of the third interstellar visitor

The ATLAS system identified 3I/ATLAS when the object was still within the Júpiter orbit. Essa early detection allowed detailed monitoring by ground- and space-based telescopes. The comet exhibited typical activity, with the release of gases and the formation of a coma and tail as it approached Sol.

Unlike ‘Oumuamua, which did not show clear signs of cometary activity, 3I/ATLAS showed a dust plume responsible for much of its reflectivity. Observações of Hubble revealed that this plume contributed to 99% of the light detected after discovery. The object reached perihelion in October 2025, about 1.4 astronomical units from Sol.

• Core estimated at 1.3 km in radius
• Approximate mass of 5 billion tons
• Hyperbolic velocity confirming external origin
• Cometary activity observed with delayed methane release

These characteristics reinforce the classification as a natural comet, although some peculiarities have generated debate in the astronomical community.

Population estimate in the external region

Avi Loeb assumes that 3I/ATLAS represents a random sample of interstellar objects. Based on the detection of one example in five years of monitoring, it infers the density of 1 to 2 similar objects within the orbit of Júpiter at any given time. Essa frequency suggests that previous surveys underestimated the presence of these bodies.

Nuvem from Oort extends to approximately 100 thousand astronomical units from Sol, marking the gravitational limit of solar influence. Nessa vast sphere, the volume allows it to accommodate ten trillion objects with characteristics similar to those of 3I/ATLAS. The total mass of this population would be equivalent to about ten Earth masses.

Voyager 1, currently 172 astronomical units, represents only a minimal fraction of this extension. Perturbações from nearby stars or the galaxy can eject objects from Nuvem from Oort, releasing them into interstellar space. The opposite also occurs, with temporary capture of external visitors.

Comparison with previously known objects

The first interstellar object, ‘Oumuamua, had a mass much lower than 3I/ATLAS, by more than four orders of magnitude. Aplicando conservative distribution by mass range, Loeb projects total mass of up to 100 Earth masses in interstellar icy rocks in the Nuvem of Esse value exceeds the rocky mass of the planets of Sistema Solar by tens of times.

Comet Borisov, the second confirmed visitor, also exhibited classic cometary behavior. However, 3I/ATLAS stands out due to the size of its nucleus and the extent of its observed antitail. Inactive Objetos, with no visible plume, would be more difficult to detect, contributing to past underestimation.

• ‘Oumuamua: elongated shape, without obvious coma
• Borisov: composition rich in carbon monoxide
• 3I/ATLAS: larger nucleus, late methane release

These differences enrich the understanding of the diversity of objects ejected from other stellar systems.

Dimensions of Nuvem of Oort and gravitational capture

Nuvem of Oort occupies a significant fraction of the distance to Alfa Centauri, the nearest star system. Cada’s star may have ejected about 100 Earth masses of icy material during planetary formation. Sistema Solar would have expelled ten times more mass in rocks than it retained in current planets.

Captured interstellar objects remain temporarily attached to Sol until external disturbances dislodge them. Essa dynamics explains the estimated presence of large population. The total mass comparable to that of native comets from Nuvem and Oort suggests a balance between local and imported material.

The extent of the cloud makes its direct exploitation unfeasible with current technology. Sondas like Voyager provide only limited data on the heliopause.

Future observations and verification of the hypothesis

Observatório Vera C. Rubin, expected to operate within the next decade, should detect bright interstellar visitors with greater efficiency. Esses data will allow us to test whether 3I/ATLAS represents a common population or an isolated case. Levantamentos systematics will clarify the actual density of objects in the outer region.

Current telescopes have already improved early identification capabilities. The experience with 3I/ATLAS prepares astronomers for future detections. Continuous Monitoramento from ATLAS and other systems contributes to growing catalog of interstellar candidates.

Particularities observed in 3I/ATLAS

The object presented alignment close to the ecliptic plane, symmetry in minijets and a prominent antitail. Essas features, although explainable by natural processes, motivated discussions about alternative origins. Most experts classify 3I/ATLAS as a natural comet from another system.

The delayed release of organic molecules such as methane adds element of interest. Comparações with solar comets reveal compositional similarities and differences. Análises spectroscopic imaging continues to refine the visitor’s chemical profile.

Implications for the formation of planetary systems

The estimated presence of large amounts of interstellar material suggests constant exchange between stellar systems. Durante early stages of formation, young stars eject excess planetesimals. Parte of this material travels through space and can be temporarily captured by other stars.

Sistema Solar retained only a small fraction of the original mass on rocky and icy planets. Most of it was dispersed, contributing to the interstellar reservoir. Essa vision reinforces models of dynamic evolution in protoplanetary disks.

Future studies will integrate data from multiple visitors to map size distribution and composition.