Straddling land and sea and teeming with life, mangrove forests are key to healthy coastal ecosystems. They're also among the most threatened habitats in the world. Learn more.

Thanks to an innovative grassroots organization called Yad Fon, southern Thailand's Trang Province is home to an inspiring example of ecosystem restoration. Learn more.

While technological advances are making it easier for the 21 million diabetics in the United States to manage healthy lives, diabetes is still a disease that requires vigilance. See how scientists are using stem cells to find a cure.

On cloudless, moonless nights, the stars are so bright over the remote village of Sutherland, South Africa, that a person can walk by starlight alone. Learn more about the village’s Southern African Large Telescope (SALT).

A series of satellite photographs taken by NASA's Mars Global Surveyor, which has been mapping Mars since 1999, raise the exciting possibility that liquid water may have existed there very recently.

Earth's water is in constant motion. It cycles through the planet's atmosphere, surface, and depths. This water cycle is fundamental to Earth’s climate — and is being dramatically affected by global warming.

Rocks older than 4 billion years are not available to study, making the first 500 million years of Earth's history particularly mysterious. But cutting-edge techniques are now allowing geologists to study survivors of Earth's early era.

In 1912, Viktor Hess took to the sky in a hot-air balloon and discovered a radioactive energy now called “cosmic rays.” Travel to Argentina to see how scientists now hope to discover at long last where the highest-energy cosmic rays are coming from.

Mapping one-quarter of the heavens in three dimensions — that’s the ambitious mission for the Sloan telescope at the Apache Point Observatory in the Sacramento Mountains of New Mexico. Find out what astronomers have discovered so far.

Vietnam harbors an astonishing range of habitats, from rain forests and dry forests to mangroves and coral reefs. It's also home to an unusually rich array of plants and animals. Find out why.