Mangrove forests rank among the world’s most valuable coastal ecosystems, shielding communities from storms, storing vast amounts of carbon and providing nurseries for countless marine species. For decades, scientists warned that these unique forests were disappearing faster than many tropical rainforests because of coastal development, aquaculture and pollution. Now, new satellite observations from Nasa present…

For centuries, owning land has meant having a place that can be measured, divided and legally transferred. Dennis Hope thought he had found an exception. In the late 20th century, while considering how to make money from property, the unemployed American turned his attention away from land on Earth and towards the moon. He had…