A new study of the interstellar comet 3I/ATLAS led by the University of Michigan shows that its water has a remarkably high content of deuterium. This form of hydrogen is comparatively less abundant in our solar system, enabling researchers to glean new insights about other planetary processes at work in our galaxy. Credit: U-M News/Hans Anderson Less than a year ago, astronomers spotted a comet passing through our solar system that originated far beyond it. The object, known as 3I/ATLAS, is