Linda looks at calendar developments from the ancient Metonic Cycle to the early Roman and Julian calendars and discusses methods of calculating the date of Easter Sunday from the advent of Christianity to Gregorian reforms and the Computus.

What are galaxies, how are they classified, how are they formed, what we understand about their lives, and how many pretty pictures can I fit in one talk.

The Hunt For Atmospheric Optical Effects - Mary has been passionate about hunting for atmospheric optics for many years. In this talk she will show us lots of the common things seen from the UK, plus some more exotic phenomena, from arcs and sundogs to noctilucent clouds and aurora.

An offbeat look at Newton's theory of gravity - featuring hollow Earths, counter-Earths Trojan asteroids, Kirkwood gaps, Lagrangian nodes, the three-body problem, and those mysterious beasts rumoured to haunt Surrey playing fields and Bodmin Moor. Already delivered on two continents!