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For the first time, the Webb telescope has spotted heavy water ice in a disk where planets are born.
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The James Webb Space Telescope peered into a disk of gas and dust around a young star where planets are born, and for the first time spotted ice made of heavy water. This water is not ordinary: in its molecules, regular hydrogen is replaced by deuterium, its heavier sibling. Such water is like a diary page, holding chemical clues from the past.
Measurements revealed an anomalously high amount of heavy water in the disk — more than in comets or meteorites. This means the ice repeatedly melted and refroze, accumulating deuterium. This cycle could explain how water arrived on Earth: some of it may be older than the Sun itself: it came from interstellar space.
Now that diary page has been read, it tells the story of water that crossed the galaxy to become our planet's oceans.