A rare interstellar comet 3I/ATLAS is hurtling through the Solar System. This would give astronomers a rare glimpse of material that has formed around another star. According to experts, it is only the third confirmed interstellar object ever discovered, following Oumuamua in 2017 and Borisov in 2019.
Discovered by the ATLAS telescope in Chile
The comet was first discovered on July 1, 2025 by the Asteroid Collision Alert System (ATLAS) telescope in Chile. The designation “3I” marks it as the third interstellar object ever identified, while “ATLAS” refers to the telescope that spotted it.
NASA later confirmed that the comet is in a hyperbolic orbit, meaning it is not gravitationally bound to the Sun and will leave the Solar System after a short pass.
According to the European Space Agency (ESA), the comet will make its closest approach to Earth on December 19, coming within about 270 million kilometers, a safe distance that does not pose a threat to the planet.
What we know about 3I-ATLAS so far
Recent observations from October 31 to November 4 suggest that the object lost significant mass during its collision with the Solar System. It also shifted its path slightly, showing signs of non-gravitational acceleration, motion caused by more than just gravity, the IFL Science report said.
China’s Mars rover captured rare images of a comet as it flew past Mars on October 3, the China National Space Administration (CNSA) said. The images were taken by Tianwen-1, China’s Mars exploration mission, marking the first successful attempt to photograph such a distant and dim interstellar target.
“The Tianwen-1 orbiter successfully observed the interstellar object 3I/ATLAS with the help of a high-resolution camera from a distance of about 30 million kilometers, one of the closest probes to it… The images clearly show the characteristic features of the comet, which consists of a nucleus and a surrounding coma, the diameter of which reaches several thousand kilometers,” the CNSA statement said.
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Nature and Composition 3I ATLAS
Preliminary evidence suggests that 3I/ATLAS is an active comet composed of volatile materials similar to those found in Solar System comets, but altered by prolonged exposure to interstellar radiation. According to NASA’s Planetary Sciences Division, early spectroscopic indications indicate the presence of carbon dioxide (CO₂) and dust emissions, consistent with the comet’s typical outgassing from the Sun’s heat.
The study, based on observations from the James Webb Space Telescope (JWST) hosted on the preprints server, suggests that the comet’s surface appears chemically weathered, suggesting it has traveled through the interstellar medium for billions of years, where cosmic rays likely altered its outer layers.
The Hubble Space Telescope estimated that the solid core of 3I/ATLAS is no more than 5.6 kilometers across, but the exact size remains uncertain due to the surrounding cloud of dust obscuring direct measurements.
Observations by the European Space Agency (ESA) noted that the comet’s bright coma extends for several thousand kilometers and is formed by the continuous emission of dust and gas as it approaches the Sun.
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