Where would the world be without oxygen? While it's hard to imagine an Earth without it, for nearly the first half of the planet's 4.5-billion-year history, Earth had no oxygen gas as part of its atmosphere.

Where would the world be without oxygen? While it's hard to imagine an Earth without it, for nearly the first half of the planet's 4.5-billion-year history, Earth had no oxygen gas as part of its atmosphere.

One of the biggest forces that's shaped planet Earth over time is microscopic in size. Explore the global impact of microbes.

Discover how the geological and climatic changes that have unfolded over millions of years in Vietnam have set the stage for an extraordinary richness of biodiversity.

Earth's early atmosphere disappeared eons ago. So how does a present-day scientist go about studying it?

See how scientists are racing to reveal Vietnam's biological riches before many species and their habitats disappear from the country's landscape due to expanding development and human activity.

Take a look at Mongolia's takhi and discover how an Asian empire was won on horseback — and how Mongolia came to be known as the land of the horse. 

By unearthing sediment deposits tsunamis leave behind, scientists can study the waves' origins, extent, and frequency — and identify locations that have the geological apparatus to produce a tsunami, but haven't in written history.

A tsunami hasn't affected the Pacific Northwest coast since 1964, yet bright-blue metal signs warning of them dot coastal streets. Find out why scientists are certain these communities are at risk.

Why did Hawaiian officials evacuate Hilo Bay in 1986 after a 7.7 earthquake but call off an evacuation in 2003 after a 7.8 one? The answer is DART. Learn more.