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| Image from the original article |
Deuterium-to-hydrogen ratios at different locations in the Solar System.
Researchers with the European Space Agency, examining Rosetta spacecraft measurements of water vapour associated with comet “Chury,” found that the isotopic composition of the comet's water vapour differed markedly from that observed on Earth.
In terrestrial water, the article states, there is normally about one deuterium atom for every 7,000 ordinary hydrogen atoms. Deuterium is an isotope of hydrogen whose nucleus contains a neutron in addition to its proton.
In water vapour released by the comet, the source reports that the proportion was approximately three times higher—about one deuterium atom for every 2,000 ordinary hydrogen atoms.
The finding, which the article says had previously been suspected as a possibility, left the much-debated origin of Earth's water unresolved.