It is always cool to repeat classic experiments. How many of us know the radius of the Earth because we determined it on our own? I haven't done this, at least not yet. For all my life I have just ...

More than 2,000 years ago, pretty much every educated human knew the Earth was round. There are some pretty obvious clues, after all. If you travel south, you see stars and constellations you’ve never ...

How far can you compress something before you reach nature’s ultimate breaking point—that is, before you create a black hole? Receive emails about upcoming NOVA programs and related content, as well ...

Students in Greece will revive Eratosthenes' calculation of the Earth’s radius and circumference, a remarkable experiment in ...