Vera C. Rubin Observatory to Discover 50 More Interstellar Comets

The Vera C. Rubin Observatory in Chile is set to revolutionize the way astronomers detect interstellar comets, with predictions indicating the potential discovery of up to 50 new objects resembling 3I/ATLAS (formally designated C/2025 N1) during its ten-year mission. This development follows the arrival of 3I/ATLAS, the third confirmed interstellar visitor, which is currently making its way back into the depths of space after its closest approach to Earth on December 19, 2025.

The arrival of 3I/ATLAS marks a significant moment in the study of interstellar objects. When the first known interstellar visitor, ‘Oumuamua, passed through our solar system in 2017, it sparked intense interest and left many questions unanswered. Fast forward to late 2025, and the conversation has shifted dramatically; rather than pondering if we will find another interstellar object, the focus is now on how many we can identify.

At the core of this transformation is the Rubin Observatory’s Legacy Survey of Space and Time (LSST). Equipped with the world’s largest digital camera, boasting an impressive 3,200-megapixel resolution, the observatory is designed to scan the entire visible southern sky every few nights. Current estimates suggest that approximately seven interstellar objects traverse the inner solar system annually; however, previous detection capabilities limited our understanding. The Rubin Observatory aims to enhance this detection rate significantly.

Early simulations predict that the observatory could identify between one and two interstellar visitors each year. Optimistic models, supported by statements from observatory representatives, indicate that the total number of discoverable objects could reach as high as 50 over the course of its mission. This potential influx of data is poised to shift interstellar studies from isolated events into a rigorous field of statistical science, with estimates suggesting approximately 10,000 such objects may currently be lurking within the orbit of Neptune.

3I/ATLAS itself has captured attention due to its unusual characteristics, providing a unique opportunity for testing new detection systems. First spotted on July 1, 2025, by the Asteroid Terrestrial-impact Last Alert System in Rio Hurtado, Chile, the comet has undergone extensive observation using various instruments, including the Hubble Space Telescope and the James Webb Space Telescope. Remarkably, the Rubin Observatory even obtained “pre-discovery” images of the comet as early as June 21, 2025, during its commissioning phase, although it was not recognized at that time.

The analysis of 3I/ATLAS has revealed it to be a carbon-rich relic, likely around 11 billion years old, originating from the Milky Way’s ancient thick disk. Unlike previous interstellar visitors, 3I/ATLAS displayed a rare “anti-tail”—a sunward-pointing spike of dust—along with gas jets indicating a rotation period of approximately 15.5 hours. These findings provide a “chemical fingerprint” reflective of a star system formed long before our own Sun existed.

The Rubin Observatory’s capacity to detect these objects early, potentially while they are still far out in the solar system, could facilitate future missions such as the European Space Agency’s Comet Interceptor. This early detection could allow for meaningful encounters with these interstellar visitors in deep space.

As 3I/ATLAS moves away from Earth, it serves as a poignant reminder of the advancements being made in astronomy. The era of merely observing occasional strays is giving way to a proactive approach, with the capability to map the debris of the galaxy as it drifts closer to our solar system. The implications for our understanding of interstellar objects are profound, potentially reshaping the landscape of astronomical research in the years to come.