A Key to the Search for Alien Life? --"Earth's Atmosphere has a Nitrogen Signature That's Unique to Our Planet"

A team of scientists reports the discovery of a planetary-scale "tug-of-war" of life, deep Earth and the upper atmosphere that is expressed in atmospheric nitrogen. Compared with other key elements of life -- such as oxygen, hydrogen and carbon --...       Related Stories The Alien Observatory -- Planet Only a Billion Years Younger Than Big Bang Found in the Milky Way's M4 Globular Cluster NASA's Hubble Space Telescope --Star-Casted Shadows Reveal Alien Planets