The sea around Iwo Island, one of the Satsunan Islands off the coast of Japan, is green because of high levels of iron Taro Matsuo et al. (2025)
For a long stretch of Earth’s history, our planet might have looked green from a distance, instead of the pale blue dot we know today.
Earth’s green period, which lasted from around 3 billion years to 600 million years ago, probably shaped the evolution of the cyanobacteria that filled the atmosphere with breathable quantities of oxygen, says at Nagoya University in Japan.
