ALMA observations of Halley-type comet 12P/Pons-Brooks reveal water with the same isotopic signature as Earth’s oceans New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed that water in the Halley-type comet 12P/Pons-Brooks has an isotopic composition virtually identical to that of Earth’s oceans. This finding strengthens the theory that comets may have played...