To celebrate the 400th Anniversary of the telescope and World Space Week. Dr Bridle will describe in pictures ‘gravitational lensing’, the bending of light by gravity, which is predicted by Einstein’s General Relativity. The mysterious dark components that constitute most of the universe do not emit or absorb light, but they do exert a gravitational attraction, and gravitational lensing is one of the most promising methods for finding out more about them. Dr Bridle will review the current observations and upcoming surveys.