Our second meeting of this semester was the latest installment in the Tea, Talk and Telescope lecture series, a series of talks which AstroSoc host in conjunction with the School of Physics & Astronomy. On this occasion, we were lucky enough to be given a lecture by Dr Robin Catchpole, a researcher from the Institute of Astronomy in Cambridge who retired from his post as Senior Astronomer at the Royal Observatory in Greenwich in 2004. With the promise of such a renowned speaker from the world of astronomy, we were very excited to be able to host Robin’s talk, and we were not disappointed.

Dr Catchpole representing the length of a light-second with a piece of string, relative to the Earth (represented by a tennis ball). Image credit: Eliot Dixon

Dr Catchpole gave an illuminating lecture on the various methods astronomers use to measure the huge distance to various objects in the night sky (known as the “cosmic distance ladder”). He began by using the recent Venus transit as an example, since it was such a transit that originally enabled us to obtain an estimate for the size of the Solar System, our first step to understanding how far away astronomical objects are. He then ran through the cosmic distance ladder, explaining what classes of object each step is applicable to, and how astronomers are able to use the available information to calculate the distance to these objects, ranging from simple parallax methods for nearby stars to type 1a supernovae for distant galaxies, until we reach the edge of the observable universe. He also took the opportunity to show us simulations of how asterisms such as the Southern Cross looked completely different in the past and will look completely different in the distant future due to movement of stars within the Milky Way galaxy, tying in his interest in archaeology to explain how ancient artefacts containing astronomical data can be dated from the positions of the stars (including the Australian flag).

We were very pleased by the interest shown in this event and hope that everybody who came along will continue to attend our public lectures in the future. For details of past and upcoming events please visit our outreach website at www.talkandtelescope.org.uk.