On July 1, 2025, a mysterious object was detected entering our Solar System by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Río Hurtado, Chile, supported by the DOE and NSF. This object, designated 3I/ATLAS, is noteworthy as it represents only the third confirmed interstellar visitor, following 1I/”Oumuamua in 2017 and 2I/Borisov in 2019.
Not only is 3I/ATLAS distinguished by its origin beyond the Solar System, but its peculiar behavior as it travels around the Sun has led some observers to suggest that it could potentially be an alien spacecraft or at least a highly unusual natural entity. According to NASA, follow-up analyses revealed that the comet is moving at an approximate speed of 60 kilometers per second relative to the Sun, following a hyperbolic trajectory that indicates its extraterrestrial origin.
The designation “3I” indicates that this is the third interstellar object cataloged, while “ATLAS” honors the discovering survey. Various observatories, such as the Hubble Space Telescope and the Gemini North Observatory in Hawaiʻi, have provided detailed images of 3I/ATLAS. Data from Hubble suggests that the nucleus of the comet measures no more than about 5.6 kilometers across, although it may be even smaller, surrounded by a diffuse coma of gas and dust.
As summer progressed, observations indicated that the comet”s tail and coma expanded as it was heated by solar radiation, a typical phenomenon associated with comets undergoing sublimation of volatile materials. Its trajectory indicates that 3I/ATLAS will reach its closest approach to the Sun, known as perihelion, in late October 2025, when it will pass within the orbit of Mars and remain a safe distance from Earth.
Experts predict that during its approach to the Sun, 3I/ATLAS will temporarily disappear from view due to solar glare, a phenomenon referred to as solar conjunction. During this period, some theorize that the object may undergo changes or maneuvers that are not observable from Earth. This has led to speculation that 3I/ATLAS could be utilizing an Oberth maneuver, a gravitational assist technique employed by spacecraft, which could allow a technologically advanced object to alter its speed and direction while close to the Sun.
Astrophysicist Avi Loeb is a prominent advocate of this theory, suggesting the remote possibility that 3I/ATLAS could have artificial origins. However, NASA has publicly dismissed this suggestion, stating as of September 2025 that there is no evidence supporting the idea of controlled thrust or artificial structures associated with the comet. Despite this, the unusual characteristics of 3I/ATLAS continue to fuel speculation.
As per NASA, the comet is not expected to pose any threat to Earth. After its passage behind the Sun in late October, it will continue its trajectory past Jupiter in March 2026, eventually exiting our Solar System.
