The basic idea of a black hole is simple. Imagine tossing a ball into the air. It goes up to a certain height, and then back down. If you toss the ball faster, the ball rises higher, but it still eventually falls. Now suppose you could toss the ball as fast as you like. Could you toss the ball so fast it doesn't fall back down?

The post Black Holes appeared first on One Universe at a Time.

We all know the Earth moves, but how can we tell? It certainly doesn't feel like we're spinning around the Earth. But there is a simple experiment that can show the motion of the Earth, known as a Foucault pendulum. It's an experiment you can do at home with a baseball, a hook screw and some string.

The post And Yet It Moves appeared first on One Universe at a Time.

It was once thought that there was a planet closer to the Sun than Mercury. It was a planet they called Vulcan.

The post The Search for Vulcan appeared first on One Universe at a Time.