Nations worldwide maintain territories for strategic and military purposes, often remnants of colonial empires.

Mars may have been a "blue planet" with an ocean the size of today's Arctic Ocean, a new study suggests.

Ancient microbial activity preserved in deep seafloor sediments challenges assumptions about where fragile traces of early ...

U p to 98 percent of Antarctica is caked in miles-thick ice sheets, some of which formed millions upon millions of years ago.