Brown scientists: Water shows moon, Earth had common origin

PROVIDENCE, R.I. -- Rocks brought back by the Apollo 15 and Apollo 17 astronauts indicate a common origin for the moon and planet Earth, bolstering the theory that an apocalyptic collision eons ago between Earth and an unknown planet-sized body gouged out debris that gave birth to the moon during the chaos that dominated the early solar system.

Prof. Alberto Saal, of Brown University's geology department, said he and three colleagues reached that conclusion after studying atomic signatures of water trapped within the rocks.

The just-published new theory drew upon work by Brown scientists and others during the past several years that led to the discovery of water on the moon, previously regarded as arid.