The planet Venus may have been habitable for billions of years, Nasa scientists have calculated.

New computer models of the climate history of the second planet from the Sun, show that until around 700 million years ago temperatures ranged from 68F (20C) to 122F (50C), cool enough for liquid water.

In the 1980s, Nasa’s Pioneer Venus mission found hints that the planet once had a shallow ocean, but because it receives far more sunlight than Earth, scientists believed it had quickly evaporated before life could become established.

With no water left on the surface, carbon dioxide rose in the atmosphere, triggering a runaway greenhouse effect that created current conditions.

Today Venus has a crushing carbon dioxide atmosphere 90 times as thick as Earth’s and temperatures at the surface reach 864 degrees Fahrenheit (462C), making life impossible.