Interstellar Comet 3I/ATLAS zips past Sun, to be monitored by Mars and Jupiter spacecraft

ESA and NASA Track Interstellar Comet 3I/ATLAS During Solar Flyby (Image: International Gemini Observatory/NOIRLab/NSF/AURA/Shadow the Scientist)

Astronomers are monitoring closely 3I/ATLAS, an interstellar comet that is moving through our solar system. Spotted initially in July 2025 from Chile, the comet moves at the incredible 130,000 mph. Its unusual trajectory shows it comes from beyond our solar system, making it only the third known interstellar object to visit Earth’s neighbourhood. Scientists are racing to gather data before it moves behind the sun.

How ESA Spacecraft Will Observe 3I/ATLAS

The European Space Agency is using Mars and Jupiter missions to monitor the comet in real time. Observing from beyond Earth allows instruments to track the comet even when Earth-based telescopes lose sight. Mars orbiters, including Mars Express and ExoMars Trace Gas Orbiter, will observe the comet between October 1 and 7. The spacecraft will pass as close as 30 million kilometres on October 3. NASA’s Psyche mission, en route to asteroid 16 Psyche, will also collect data. Later, ESA’s Jupiter Icy Moons Explorer, or JUICE, will focus on the comet from November 2 to 25, observing its active phase near perihelion.

Why Studying 3I/ATLAS Matters

The comet will become highly active as solar heat vaporises its ice, creating a halo of gas and dust with a streaming tail. Scientists will try to quantify its chemical composition by measuring the released gases and dust. Comparing that information with comets in our solar system may show whether other planetary systems have the same ingredients to build worlds. If it is different, it could mean exotic ingredients from a different star system. Watching 3I/ATLAS during this stage will give us unprecedented insight into what interstellar comets are.