Ancient Martian ocean held more water than Earth's Arctic Ocean

An ancient ocean on the surface of Mars held more liquid water than the Earth's Arctic Ocean, scientists believe.

The huge swathe of water once covered what is now the planet's arid northern plains and would have contained at least 20 million cubic kilometres (12.4 million cubic miles) of water.

That was during the planet's wet Noachian period, which ended about 3.7 billion years ago when life was just emerging on Earth.Since then, 87% of the water has been lost to space, according to the new research reported in the journal Science.

Scientists from Nasa made the discovery after measuring atomic signatures of water in the Martian atmosphere using powerful Earth telescopes.

An ancient ocean containing the lost water would have covered 19% of the planet's surface.It would have had a greater volume than the Arctic Ocean, which contains 18,750,000 cubic kilometres (11.7 million cubic miles) of water.

By comparison, the Atlantic Ocean covers 17% of the surface of the Earth and contains more than 310 million cubic kilometres (192.6 million cubic miles).