... solar system . ... Solar system ice: source of Earth's water . Scientific findings contradict prevailing theories about the relationship between comets and water-bearing carbonaceous chondrites and suggest that meteorites, and their parent asteroids, are the most likely sources of Earth's water. ... Therefore, by comparing the deuterium content of water in carbonaceous chondrites to the deuterium content of comets, it is possible to tell if they formed in similar reaches of the solar system. ...