Water arrived on Earth earlier than thought
Planet’s oceans share common origin with water on asteroid Vesta
Water might have arrived on Earth as the planet was forming, according to new measurements of water in ancient space rocks. The findings could help planetary scientists piece together the development of asteroids and rocky planets.
About 4.6 billion years ago, the solar system began as a spinning disk of searing gas and dust around the newborn sun. The dust stuck together, gradually growing into pebbles and rocks that would go on to become asteroids and planets. Researchers know that Earth acquired its water when the solar system was less than about 200 million years old, based on measurements of moon rocks brought back by the Apollo astronauts. But until now, no one knew whether water fell to Earth during its molten, fragmented stage or arrived much later as the planet cooled and solidified.