Some of the most tantalizing hints in the search for extraterrestrial intelligence have not been messy or chaotic, but eerily ...

A single metallic boulder sitting in an ancient Martian riverbed is forcing scientists to rethink what they thought they knew about the Red Planet. The rock, an apparent interplanetary visitor, is not ...

Downtown San Francisco glows at twilight as the Transamerica Pyramid and skyscrapers rise in the background above low ...