Interstellar Comet 3I/ATLAS: Characteristics and Future Trajectory

Astronomers have recently discovered the interstellar comet 3I/ATLAS, detected on July 1, 2025, as it travels through the Solar System. This celestial object is unique, being only the third known interstellar object to be identified, subsequent to 1I/'Oumuamua in 2017 and 2I/Borisov in 2019. Initial observations suggest that 3I/ATLAS is significantly larger and potentially older than its predecessors, making it a subject of intense interest within the astronomical community.

3I/ATLAS was first identified when it was approximately 4.5 astronomical units from the Sun, placing it within the orbit of Jupiter. Currently, it is moving at a speed of nearly 60 kilometers (37 miles) per second, which is expected to increase as it approaches the Sun. Its closest approach to the Sun will occur on October 29, 2025, at around 1.36 astronomical units, and it will come closest to Earth in December 2025, at a distance of 1.8 astronomical units.

The origin of 3I/ATLAS has been traced back to the thick disk of the Milky Way, a region characterized by older stars and stellar remnants. This finding is crucial as it provides insights into the age of the comet. Preliminary analyses suggest that it could be between 3 and 11 billion years old, indicating that it may predate the formation of our Solar System. Dr. Chris Lintott, an astrophysicist at the University of Oxford, remarked, "We think there's a two-thirds chance this comet is older than the Solar System, and that it's been drifting through interstellar space ever since."

The size of 3I/ATLAS is another notable feature; it is estimated to be about 10 kilometers across, significantly larger than both 1I/'Oumuamua and 2I/Borisov, which measured approximately 400 meters and 975 meters in length, respectively. Observations conducted with the Gemini North telescope have revealed a fuzzy coma around the comet, comprised of dust and gas, which is expected to become more active as it approaches the Sun. According to Dr. Darryl Seligman of Michigan State University, "3I/ATLAS likely contains ices, especially below the surface, and those ices may start to activate as it nears the Sun."

The implications of 3I/ATLAS's discovery extend beyond its physical characteristics. Its presence suggests that interstellar objects may be more common in our Solar System than previously understood. This revelation is particularly exciting in light of the upcoming ESA/JAXA Comet Interceptor mission, slated for launch in 2029, which aims to study comets in detail.

As astronomers continue to monitor 3I/ATLAS, further observations will provide more data on its composition and behavior. The study of this comet not only enhances our understanding of the Solar System's dynamics but also opens up new avenues for exploring the history and evolution of celestial objects in our galaxy. The scientific community is eagerly awaiting the next set of observations that will shed light on this remarkable interstellar traveler.