Harvard astrophysicist confirms Earth’s safety during passage of interstellar comet 3I/Atlas

Astrophysicist Avi Loeb, from Universidade Harvard, released a conclusive analysis of the passage of the interstellar comet 3I/Atlas close to Terra in December 2025. The study, based on data from Telescópio Espacial James Webb, completely rules out any risk to the planet, despite the detection of cyanide in the gaseous composition of the celestial object. The comet reached its closest approach on December 19, maintaining a safe distance of approximately 269 million kilometers, a determining factor for the absence of direct threats.

Descoberta and Interstellar Visitor Trajectory

Comet 3I/Atlas was identified on July 1, 2025 by the ATLAS astronomical survey system, located at Chile. Sua detection quickly caught the attention of global astronomers due to the unusual trajectory. Análises orbitals confirmed that the object followed a hyperbolic path, indicating an origin in interstellar space, not gravitationally bound to Sol. Sua’s speed exceeding 60 kilometers per second reinforced this classification, placing it on the select list of visitors from other star systems, alongside ‘Oumuamua and Borisov.

The comet’s perihelion occurred on October 29, 2025, at 1.36 Unidades Astronômicas from Sol. Após this maneuver, continued its journey, passing through the closest point to Terra in December. The minimum separation between the comet’s trajectory and Earth’s orbit was calculated at more than 55 million kilometers, a safety margin that eliminated any possibility of collision. Telescópios, like Hubble and James Webb, recorded an evolution in their appearance, which went from an initial reddish coma to greenish tones, a phenomenon associated with the release of specific gases under the influence of solar radiation.

Composição chemistry revealed by James Webb

The spectroscopic analysis carried out with the Telescópio Espacial James Webb was fundamental in revealing the chemical secrets of 3I/Atlas. The data revealed that carbon dioxide was the dominant component sublimating from its icy core, a feature observed in many comets. The detection of other compounds provided valuable insights into the object’s place of origin.

• Cianeto (CN) and cyanogen identified in the gas cloud surrounding the nucleus.
• Monóxido of carbon, water vapor and nickel found in the instruments of the Webb.
• Ausência of significant non-gravitational accelerations indicated activity driven by natural sublimation.

Embora cyanide presence is common in Sistema Solar comets, its quantification in interstellar object is crucial to compare chemistry of different planetary systems. The metallic elements found offer clues about the conditions for the formation of the comet in deep space.

Avaliação of risks and dispersion of materials

Avi Loeb used mass loss rate data from 3I/Atlas, measured by James Webb, to calculate dispersion of its materials in space. Seu’s main focus was to determine the fate of gases, including cyanide, that break away from the nucleus as the comet approaches Sol. Calculations have shown that these gases are quickly swept away by the solar wind and radiation pressure, forming a tail that extends for millions of kilometers, but which dilutes to insignificant levels over great distances.

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The vast spatial separation prevents the cloud of gas and dust that forms the comet’s coma from interacting significantly with the Earth’s atmosphere. The solar wind acts as an additional shield, pushing particles away from the planet, ensuring that the passage is a purely observational event. Qualquer solid particle that could hypothetically cross the path of Terra would be microscopic in size and would completely disintegrate upon entering the atmosphere.

Observações Scientific and Interstellar Comparisons

A global network of observatories, including Gemini and Hubble telescopes, followed 3I/Atlas during its passage. Images captured by these instruments showed fascinating details, such as complex jets emanating from the core and ever-expanding coma. Data collected by space agencies such as NASA and ESA were compiled to create a complete profile of the object, reinforcing its classification as a comet of natural origin.

Essas comparative observations with previous interstellar visitors, ‘Oumuamua and Borisov, are vital to building census of the properties of objects formed in other stellar systems. Cada interstellar object crossing Sistema Solar offers free sample of material from another part of the galaxy, an invaluable gift for planetary science. Studying the composition of 3I/Atlas helps scientists understand the diversity of planetary building blocks that exist around other stars.

Conclusão on planetary security

The calculations of Loeb and observations from multiple telescopes converge to the same certainty: the passage of comet 3I/Atlas was a completely safe astronomical spectacle for Terra. The combination of massive orbital distances, the physics of gas dispersion by the solar wind and the natural protection offered by the Earth’s atmosphere ensured that the event did not pose any planetary risk. The analysis reinforces confidence in modern scientific ability to monitor and assess potential threats from space.