New evidence points to the evolution of the ability for bacteria to grab nitrogen from the atmosphere some 3.2 billion years ago, about 1.2 billion years earlier than thought—with implications for finding extraterrestrial life. Lee Billings reports

A dwarf galaxy near the Milky Way may consist of more dark matter than regular matter.* Clara Moskowitz reports

The oldest group of terrestrial worlds now known formed some 11.2 billion years ago, more than six billion years before our sun and planets. Clara Moskowitz reports