Note: Select a region before finding a country.
Presidential candidates Hillary Clinton and Donald Trump squared off one-on-one for the first time in a combative opening debate. More
Atmospheric oxygen levels have declined over the past 1 million years, although not nearly enough to trigger any major problems for life on Earth, a new study finds.
Good news on the alien-life-hunting front: The towering plumes emanating from Jupiter's ocean-harboring moon Europa appear to be real.