Have you ever stumbled upon a discovery while looking for something completely different? See what surprises astronomers found as part of the Sloan Digital Sky Survey.

What is the Universe’s arrangement today? What did it look like at its birth? And how did we get from then to now? These are just some of the “Big Questions” astronomers are making headway answering.

There’s only one star that astronomers have a firm grasp on: the Sun. Fundamental facts about other stars remain elusive. Find out how a powerful interferometer atop Mount Wilson in Southern California hopes to change that.

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.

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.

The takhi is the only true wild horse left in the world. The so-called "wild" horses that abound in Australia and North America are actually feral. Find out what it means when a domestic animal becomes feral. 

Takhi horses became extinct in the wild in the late 1960s — but since 1997 they have been successfully breeding in the wild. Learn about the efforts behind this successful reintroduction. 

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. 

Modern horses are part of the family Equidae. The fossil history of Equidae is well documented, but new evidence about its evolutionary history — and new interpretations of it — continue to accumulate. 

In 1991, the larvae of a striped, thumbnail-sized European shellfish floated quietly into the Hudson River. Find out how the zebra mussel invasion has been both tenacious and transformative.