...Scientists have been keeping a close watch on those changes, both to ensure there’s nothing unexplainable by our current understanding, but also to compare 3I/ATLAS to both previous interstellar visitors as well as comets in our own solar system. A recent paper from European researchers describes how the changes in a particular material ratio in 3I/ATLAS’ coma fit with our current understanding of cometary geology.That ratio is the nickel to iron (Ni/FE) abundance ratio. It has been measured for two decades, including on twenty in-system comets as well as 2I/Borisov, the last known interstellar visitor our solar system had. However,...