NASA Confirms Interstellar Object 3I/ATLAS as Comet After Mars Flyby

NASA officially declared on Wednesday, November 19, 2025, that the interstellar object designated 3I/ATLAS is unequivocally a comet, providing fresh imagery to support the scientific consensus and quell public speculation regarding an artificial origin. This confirmation followed extensive observations gathered by a coordinated network of instruments, including telescopes and spacecraft positioned near Mars. The object, the third confirmed interstellar visitor to the Solar System after 1I/ʻOumuamua and 2I/Borisov, was initially detected in July 2025 by the NASA-funded ATLAS (Asteroid Terrestrial-impact Last Alert System) telescope in Río Hurtado, Chile.

Key to the confirmation was the object’s recent trajectory through the inner Solar System, which included a close passage by Mars in early October 2025, at a distance of approximately 19 million miles, or 28 million kilometers. The object reached its perihelion, its closest point to the Sun, on October 29, 2025, passing inside the orbit of Mars at 1.36 AU, or about 203 million kilometers from the star. The period of intense public discourse surrounding its nature was reportedly exacerbated by a delay in NASA’s official response due to a concurrent United States government shutdown.

During the November 19 briefing held at NASA's Goddard Space Flight Center in Greenbelt, Maryland, officials provided definitive statements. Amit Kshatriya, NASA Associate Administrator, concluded that the object behaves consistently with a comet. Nicola Fox, Associate Administrator of NASA's Science Mission Directorate, reinforced this, noting the absence of any observed technosignatures suggesting artificial construction. Dr. Tom Statler, a NASA scientist, highlighted the profound scientific value, describing the comet as a rare 'window into the deep past,' suggesting it predates the formation of the Sun and Earth, potentially being up to seven billion years old.

Observations from multiple international and agency assets were crucial in characterizing 3I/ATLAS. The Hubble Space Telescope and the James Webb Space Telescope (JWST) provided detailed spectral data, with JWST detecting the release of carbon dioxide and water ice from the comet's coma. The European Space Agency (ESA) leveraged its assets near Mars; the Mars Express and ExoMars Trace Gas Orbiter observed the object during its October flyby, improving trajectory predictions by a factor of 10. Even the STEREO-A spacecraft, via its Heliocentric Imager-1 instrument, captured colorized stacked images in late September and early October 2025.

Despite the official confirmation, the object’s initial characteristics—including its high speed of approximately 210,000 km/h or 130,000 miles per hour relative to the Sun, and its unusual trajectory—initially fueled speculation about an engineered origin, mirroring the debate surrounding 1I/ʻOumuamua. However, the detection of natural emissions, such as cyanide and atomic nickel in the coma, and a radio signal consistent with natural hydroxyl radicals via South Africa's MeerKAT radio telescope, provided the final scientific evidence solidifying its cometary classification.

Looking forward, 3I/ATLAS poses no threat to Earth, with its closest approach to our planet scheduled for Friday, December 19, 2025, at a distance of about 167 million miles (269 million kilometers). Following this, the object is projected to pass the orbit of Jupiter in the spring of 2026 before permanently exiting the Solar System, continuing its voyage through the galaxy. The collaborative observation campaign, involving instruments from Earth, Mars orbit, and beyond, represents a significant test case for planetary defense experts studying the paths of interstellar visitors.