6+ day, 11+ hour ago   (404+ words) We usually depict the early Earth as a restless planet, exposed to ultraviolet radiation, struck by lightning, and constantly hit by meteorites. These widespread energy sources are typically thought to have played a role in forming life’s building blocks. But…...

2+ week, 7+ hour ago   (377+ words) Mars has always been a planet of contrasts. Its northern hemisphere is a vast, flat lowland, while the southern half is rugged with towering mountains and deep craters. Now scientists have discovered that this asymmetry extends deep beneath the surface:…...