What’s the origin of water on Earth?

Wednesday 14th May 2025, 12.30pm

With more than 70% of its surface covered in water, Earth is rightly known as the “blue planet”. But where did this water – so essential to life – originate? While some theories suggest that hydrogen was delivered to Earth from space via asteroids, new research indicates that the building blocks for water may have been present on our planet all along. We chat to Tom Barrett from Oxford’s Department of Earth Sciences to find out more.