In astronomy, the point of no return is known as a black hole - a region in space where the pull of gravity is so strong that nothing - not even light - can escape. Now, an international team, led by ...

I don't know where he got this idea (surely not from the internet), but Eratosthenes estimated the radius of the Earth by looking at two shadows at two different locations on the Earth. This diagram ...

Puzzling problem: Karsten Schuhmann (left) and Aldo Antognini of the Paul Scherrer Institute inspect the laser system that was used for the laser spectroscopy measurements on muonic deuterium.