The oldest piece of Mars on Earth and a news roundup (21 November 2014)

Eric Hand discusses the winding history of the Black Beauty meteorite–a 4.4 billion-year-old piece of Mars. Online news editor David Grimm brings stories on bacteria’s role in the blood-brain barrier, the “ice-pocalypse”, and why only 10 percent of galaxies may host complex life. Hosted by Sarah Crespi. [Img: © Joe McNally]