4.6 billion years ago
Thereof, how do scientists think the Earth's oceans were formed?
Scientists believe that just after the Earth formed, it was very hot and dry. Theory also suggests that millions of water-rich comets and asteroids bombarded our planet around 3.8 billion years ago, neatly explaining why oceans later appeared.
Where did the Earth's oceans come from?
Scientists think that over time, all these collisions filled the oceans. Another idea is that ocean water came from deep inside the earth. It was brought to the surface when volcanoes erupted. Scientists think soon after the earth was formed, there was a long period of massive volcanic eruptions.