Hidden Details of Earth’s Atmosphere Revealed By Orbiting Spacecraft

Watching the stars set from the surface of the Earth may be a romantic pastime but when a spacecraft does it from orbit, it can reveal hidden details about a planet’s atmosphere.

The technique is known as stellar occultation. Jean-Loup Bertaux, Service d’Aeronomie du CNRS, France was the first to suggest its use on an ESA mission. It works by watching stars from space, while they drop behind the atmosphere of a planet under investigation, before disappearing from view below the planet’s horizon.

Researchers find origin of ‘breathable’ atmosphere half a billion years ago

Ohio State University geologists and their colleagues have uncovered evidence of when Earth may have first supported an oxygen-rich atmosphere similar to the one we breathe today.The study suggests that upheavals in the earth’s crust initiated a kind of reverse-greenhouse effect 500 million years ago that cooled the world’s oceans, spawned giant plankton blooms, and sent a burst of oxygen into the atmosphere.