China’s Tianwen-1 captures interstellar comet 3I/ATLAS near Mars
8 reported1 unconfirmed
China's Tianwen-1 spacecraft photographed the interstellar object 3I/ATLAS as it passed near Mars, according to the China National Space Agency (CNSA). The orbiter used its high-resolution camera to capture the comet from about 30 million km away. Tianwen-1 has been orbiting Mars for four years and eight months, making it one of the closest spacecraft to observe the interstellar object since its discovery on May 7, 2025. The new images show a visible tail and a cloud of gas and dust (coma) surrounding the nucleus, supporting the conclusion that 3I/ATLAS is a comet. Researchers combined multiple images into an animation tracing the comet's movement toward its closest approach to the Sun. The observations add to evidence that 3I/ATLAS contains water and other volatile materials that began escaping as the object warmed. On October 3rd, both European orbiters Mars Express and ExoMars Trace Gas Orbiter also photographed 3I/ATLAS, though the comet appeared roughly 10,000 to 100,000 times fainter than sunlit features on Mars.
What’s reported
Tianwen-1 photographed 3I/ATLAS from about 30 million km (18.6 million mi) away.
The comet was discovered on May 7, 2025.
Tianwen-1 has been orbiting Mars for four years and eight months.
The comet is 5.6 km (3.5 mi) in diameter.
The comet was moving at around 58 km/s (36 mi/s), with relative motion to Tianwen-1 reaching approximately 86 km/s (53.5 mi/s).
On October 3rd, Mars Express and ExoMars Trace Gas Orbiter also photographed 3I/ATLAS.
The comet appeared 10,000 to 100,000 times fainter than sunlit features on Mars.
HiRIC's exposure time has not been released publicly.
Open questions
The exposure time of Tianwen-1's High-Resolution Imaging Camera (HiRIC) has not been released publicly.
Key figures
China National Space Agency (CNSA)
Matthew Williams (original writer for Universe Today)
Sources: ScienceDaily
