I am Professor of Observational Astronomy at the Hamburger Sternwarte, which is an institute in the Department of Physics of the University of Hamburg.

My scientific interests are in extragalactic astronomy and observational cosmology. I try to unravel the mechanisms that are responsible for the evolution of galaxies by studying large samples of galaxies obtained from imaging and spectroscopic surveys at various wavelengths. I also study the tenuous intergalactic medium, worry about why the expansion of the Universe is accelerating, and contribute to the development of new astronomical instruments.

I am also a keen and active science communicator. I host the Hubblecast and the ESOcast, two popular video podcasts featuring the latest science, news and images from the Hubble Space Telescope and the European Southern Observatory. Other productions I have been fortunate enough to be involved with include the movie Eyes on the Skies, a documentary celebrating the 400th anniversary of the telescope in the International Year of Astronomy 2009, The Eye 3D, an award-winning 3D documentary about ESO's Paranal Observatory that was released in Oct 2009, and the Austrian TV series Hubble – Mission Universum. I frequently give media interviews as well as public talks at science events, conferences, universities, schools, astronomy clubs, public observatories, adult education centres, etc. If you are looking for an interview partner or public speaker, feel free to contact me.

Before joining the University of Hamburg I was a staff astronomer at the European Southern Observatory, working on the science of the European Extremely Large Telescope, the world's largest optical and near-infrared telescope (currently under construction). Previously, I was a Fellow at ESO and a postdoc at the Universities of Edinburgh and St. Andrews. I obtained my PhD from the University of New South Wales in Sydney, Australia, under the supervision of Profs. John Webb and Bob Carswell (IoA Cambridge), and studied Physics at the University of Bonn.