Why scientists need to search for alien life on purple planets

Billions of years ago, when microbial life first emerged on Earth, our planet would have appeared purple from space. Armed with this knowledge, scientists now say we should be on the lookout for exoplanets tinged in a similar purple hue — a possible sign of extraterrestrial life. » 11/13/13 7:20am 11/13/13 7:20am