Looking through a telescope takes us on a journey through time as well as space. It takes time for light to cross the vast expanse of space, so when we look at distant objects through our telescopes we see them as they appeared long ago.... click to read more

In 1933, Fritz Zwicky, observing the Coma galaxy cluster, noted that single galaxies were moving too fast for the cluster to remain bound, according to the measure of visible mass. Only a far more significant amount of invisible matter could explain the strong gravitational force... click to read more

Einstein's general theory of relativity predicted that gravity not only acts between two masses but also affects light which has no mass. We cannot see this effect in everyday life, but when light travels over vast intergalactic distances and is affected by the incredibly large... click to read more