In 1933, the Bulgarian-born astronomer Fritz Zwicky, working in the U.S., noticed unexpected motion in galaxies. Zwicky inferred gravitational effects of unseen material which he called Dark Matter.

A supernova is one of the most powerful and mysterious phenomena in the universe. It’s an event that occurs when a star ...

The Swiss astronomer Fritz Zwicky 2 was the first to recognize that the rapid motions of galaxies — of around 2,000 kilometres per second — in the Coma cluster could be explained only by ...