The rocky planets—Mercury, Venus, Earth and Mars—were born of similar material around the same time. Yet only one of them supports life. Were Earth's neighbors always so extreme? And is there somewhere else in the solar system life might flourish?
Discover the science behind Leonardo da Vinci's masterpieces—and Mona Lisa's iconic smile.
Can new engineering techniques help prevent deadly bridge collapses?
Amazing fossils reveal how mammals took over after an asteroid wiped out the dinosaurs.
