The interstellar comet 3I/ATLAS is set to reach its perihelion, the closest point to the Sun, on October 29, 2025. Discovered on July 1, 2025, by the ATLAS monitoring system in Chile, this comet will come within 1.35 astronomical units of the Sun. Scientists emphasize that there is no risk of impact with Earth, as its hyperbolic orbit will take it back to interstellar space after its brief visit.
The Gemini South Observatory, located in Cerro Pachón, Chile, captured multicolored images of the comet using the GMOS spectrograph on August 27, 2025. These images reveal a wide, bright coma and a prominent tail extending away from the Sun, significantly larger than previous observations. This increase in activity suggests that the comet is becoming more dynamic as it enters the inner solar system.
Astronomers have also obtained the spectrum of the comet”s light, which is crucial for analyzing its chemical composition. Initial results indicate that the dust and ice of 3I/ATLAS resemble those found in native solar system comets. This similarity points to shared processes in the formation of planetary systems around different stars.
Interstellar comets are exceptionally rare, with only two confirmed prior to 3I/ATLAS: 1I/”Oumuamua in 2017 and 2I/Borisov in 2019. Studying these objects provides scientists with access to primordial material from other stellar systems, a unique opportunity not available through other means.
The European Space Agency (ESA) has deployed several of its missions to observe the comet from advantageous positions. The Mars Express and ExoMars Trace Gas Orbiter examined 3I/ATLAS earlier in October as it made its close approach to Mars. The JUICE mission, which stands for “Jupiter Icy Moons Explorer,” will study the comet between November 2 and 25, 2025, while it remains highly active following its perihelion.
However, the unusual behavior of 3I/ATLAS, including phenomena such as the appearance of an “anti-tail,” has sparked speculation and misinformation on social media. In response, NASA and the scientific community have reiterated that the comet poses no threat and that its study represents a remarkable opportunity for modern astronomy.
