In 1836, Charles Darwin and his colleague Joseph Hooker visited Ascension Island, really just a barren pile of volcanic basalt topped by an old cinder cone, ironically named Green Mountain.

There were very few plants, but some soldiers had successfully grown a vegetable garden in the volcanic soil. This gave Hooker a crazy idea. He contacted his father, the director of the botanical garden in London, and persuaded him to send plants.

Hooker and Darwin believed that if they could establish a thriving plant colony on the island, it would trap water and self-perpetuate.

By 1850, the Royal Navy had brought dozens of species from Europe, Argentina and South Africa. Just 20 years later, Hooker and Darwin were proved correct. The plants thrived and still do today.

Near the coast there are now grasses, shrubs and mesquite. Higher up the slope, cactus and acacia trees grow in the increasing moisture.

Above 2000 feet, the island becomes a misty cloud forest of ferns, eucalyptus, bamboo and evergreens, with food crops like fruit trees, coffee and ginger.

A water catchment system built long ago is no longer needed since the island makes its own wet microclimate.

Green Mountain is now in fact green—a signal that similar efforts, in places with the right potential for rainfall, could regreen other barren landscapes—maybe even on other planets!