Interstellar Comet 3I/ATLAS Captured in Rare Mars Flyby Images

European Space Agency (ESA) orbiters have captured images of interstellar comet 3I/ATLAS during its close approach to Mars. This marks the third confirmed interstellar object to enter our solar system. The images, taken on October 3, 2025, by the ExoMars Trace Gas Orbiter and Mars Express, depict the comet as a bright, fuzzy white dot moving against a backdrop of distant stars.

Nick Thomas, principal investigator of the CaSSIS camera on the ExoMars orbiter, noted the difficulty of the observation, stating,

"This was a very challenging observation for the instrument. The comet is around 10,000 to 100,000 times fainter than our usual target."

Discovered in July 2025, 3I/ATLAS is traveling at approximately 193,000 mph (310,000 kph) and is estimated to be about 7 miles (11.2 kilometers) in diameter, making it the largest interstellar object observed to date. The comet poses no threat to Earth and is expected to make its closest approach to the Sun in late October, passing between the orbits of Mars and Earth.

ESA scientists will continue analyzing data from both orbiters, combining multiple images from Mars Express in hopes of detecting the faint comet. Further observations are planned as 3I/ATLAS approaches the Sun, providing a unique opportunity to study an interstellar visitor.