ESA Tracks an Interstellar Comet Passing Through Our Solar System!

In July 2025, automated systems detected Comet 3I/ATLAS, an object of particular interest because its trajectory indicated it originated from *outside* our solar system. This marks only the second interstellar comet ever observed, following 'Oumuamua in 2017. The European Space Agency (ESA) recognized the significance of this discovery and sprang into action to monitor its progress through our solar system. ESA astronomers immediately coordinated observations using ground-based telescopes located in Hawaii, Chile, and Australia. These initial observations allowed them to refine the comet's orbit and predict its future path. However, the real breakthroughs came from using powerful space-based observatories like the NASA/ESA Hubble Space Telescope and the NASA/ESA/CSA James Webb Space Telescope. These space telescopes offer unique advantages. They can observe the comet without the blurring effects of Earth's atmosphere, allowing for sharper images and more precise measurements. Furthermore, Webb's infrared capabilities are crucial for analyzing the comet's composition. By studying the light reflected and emitted by the comet, scientists can identify the types of molecules present, such as water, carbon dioxide, and other volatile compounds. Understanding the composition of interstellar objects like Comet 3I/ATLAS is crucial for understanding the formation and evolution of planetary systems in general. This comet carries material from its home star system, essentially delivering a sample of a distant world to our doorstep. By comparing the composition of 3I/ATLAS with that of comets within our own solar system, we can gain insights into the similarities and differences between stellar nurseries, informing our understanding of the origins of planets and potentially even life itself. The data collected is being used to create models of the comet's nucleus and coma (the fuzzy atmosphere surrounding the nucleus), as well as to estimate the size and density of the comet. This will paint a more complete picture of where this object came from and how it interacted with its original star system. ESA will continue to monitor interstellar objects that enter our solar system in the future, using ever-improving observational technologies and techniques. The study of these celestial wanderers promises to reveal profound secrets about the universe beyond our solar system and the processes that shape planetary formation everywhere.