A Rare Visitor From Beyond
Discovered in July 2025 by an ATLAS telescope in Chile, 3I/ATLAS is only the third confirmed interstellar object to visit our solar system, following ‘Oumuamua in 2017 and comet Borisov in 2019. Its trajectory — open rather than closed — makes clear it did not originate in our system.
Ground-based observatories tracked it until late September, but now Earth has lost line of sight as the comet slipped behind the sun. For astronomers, this active perihelion phase is the “make-or-break” moment.
ESA is stepping into the breach. Between October 1–7, its Mars orbiters (Mars Express and the ExoMars Trace Gas Orbiter) are focused on 3I/ATLAS. On October 3, the object passes within 30 million km of Mars. Meanwhile, NASA’s Psyche mission — en route to the asteroid belt — will also record observations.
The most critical data may come in November, when ESA’s Jupiter Icy Moons Explorer (JUICE) will monitor 3I/ATLAS just after its closest solar approach.
Global Stakes and Warnings
Harvard’s Avi Loeb, known for his work on interstellar phenomena, submitted a whitepaper to the United Nations this week urging leaders to establish an emergency protocol. He warned that interstellar objects carry the potential for “Black Swan” outcomes — events with outsized, unpredictable consequences.
The U.N. briefing underscores how 3I/ATLAS is not just an academic exercise. The chemical clues gleaned from its vaporizing gases could answer whether planetary systems across the galaxy share common building blocks — or whether this object bears alien compounds never before seen in our solar neighborhood.
