We are pleased to invite you to a talk (at physics undergraduate level) by Dr Mark Sullivan? University of Oxford? entitled “The Transient Universe: Dark Energy and Cosmic Explosions” at 12.30pm on 4 April in Physics Lecture Theatre C (46/2005).? Mark is one of the UK’s leading figures in the use of facilities such as the Palomar Transient Factory, which is using supernovae to constrain the properties of Dark Energy.