Oxygen on exoplanets can be the result of simple chemical processes rather than biological ones.

Oxygen fills the air today, but for most of Earth’s early history it barely existed. Scientists say the atmosphere did not hold steady oxygen until about 2.33 billion years ago, during the Great ...

Alien life on a planet with low levels of oxygen might never be able to develop technology because combustion would be impossible. This bottleneck for creating advanced civilisations may also help ...

PASADENA, Calif.–Two and a half billion years ago, when our evolutionary ancestors were little more than a twinkle in a bacterium’s plasma membrane, the process known as photosynthesis suddenly gained ...