Interstellar Object 3I/ATLAS Fades

The interstellar object 3I/ATLAS is currently fading as it exits the Solar System, having made its closest approach to Jupiter on March 16, 2026. This object, observed with a 25-centimeter telescope, displayed a small non-gravitational acceleration attributed to a system of jets. Researchers have identified 22 anomalies associated with 3I/ATLAS, raising questions about its origin and nature.

Key anomalies include a mass budget discrepancy, where its inferred nucleus diameter of 2.6 kilometers and population density exceed the mass reservoir of planetary disks around low-metallicity stars. Geometrically, its retrograde trajectory is aligned within 5 degrees of the ecliptic plane, a 0.2% probability, suggesting a potentially planned trajectory. Its arrival time was also fine-tuned for close approaches to Mars (29 million kilometers) and Jupiter (54 million kilometers), while being unobservable from Earth at perihelion. The perijove distance to Jupiter was 53.6 million kilometers, nearly identical to Jupiter's Hill radius of 53.5 million kilometers.

Observations from the Hubble Space Telescope on July 21, 2025, indicated an anti-tail before perihelion that was a collimated jet, approximately ten times longer than wide, directed towards the Sun. The fading of 3I/ATLAS marks the end of a rare observation opportunity, as it departs the Solar System at 60 kilometers per second.