RC: The first that springs to mind is Copernicus's realization that the Earth wasn't the center of the Universe, as this had profound effects both scientifically and culturally. More recently, people are often surprised to learn that it was only in the 1920s that Edwin Hubble proved there were galaxies other than the Milky Way, and that the Universe is expanding. New evidence in the last few years has surprised even the astronomers, because it suggests that the Universe's expansion from the Big Bang is speeding up rather than slowing down, hinting at new fundamental physics that we don't understand. But I think what will have the biggest effect on us in modern times will be the discovery of another planet similar to Earth. The rate of progress in planet hunting suggests that such a discovery will be made in the near future.

GT: As for the rest of your career, what do you hope you will be able to discover out there?

RC: Big discoveries are fairly few and far between, and progress is more commonly made in small steps. I think most astronomers are keen to keep making their small contribution to our knowledge of the Universe. New telescopes and ever more powerful supercomputers mean that there are always new and exciting discoveries to make if you work hard enough. Very few of us see it as a 9-5 job and are happy to work long hours, the pay off being fairly frequent travel to far-off locations to use telescopes and collaborate with international colleagues, and the opportunity to learn something about the Universe before anyone else does.

GT: If readers were hoping to get into astrophysics too, what would you advise is the best way to go?

RC: I'd advise them to speak to people in the field to gauge whether it's the right path for them, as it's a long, demanding (but rewarding) road. One of my colleagues has written for would-be astronomers, which I highly recommend.