University College London (UCL) Department of Physics and Astronomy runs a public programme of science lectures:

• Weekly lecture, in term time
• For school pupils thinking about a degree in science subject
• Open to the public

http://www.ucl.ac.uk/silva/phys/department/science_centre

Recent lecture “Discovery of Exoplanets and the search for life beyond the Solar System” by  Dr Ingo Waldman.

Cameras in space are capturing images of planets as they pass across the face of their star. By analysing the light around the edge of the planet we can estimate the composition of the planet and the type of atmosphere it has. It turns out that there is a vast number of planets that are broadly similar to Earth.