In 1990, after travelling through the solar system for 13 years, NASA’s Voyager 1 spacecraft turned to look back at the inner solar system and captured a final few images before its cameras lost power.
One of these images featured a miniscule bluish-white speck, suspended precariously among colossal bands of scattered sunlight: Earth, seen from six billion kilometres away. Some time in the early 1990s, as a child growing up in apartheid South Africa, I stumbled upon this image in a doctor’s waiting room. I was awed to think that this ‘pale blue dot … a mere mote of dust, suspended in a sunbeam … a lonely speck in the great enveloping cosmic dark’ (to quote Carl Sagan) has been home to every human and known form of life that has ever existed. I was staggered by the contrast between humanity’s imagined self-importance, and the objective tininess and fragility of our entire planet.
Soon I wanted to know: are there other pale blue dots somewhere out in space? Might such planets also be teeming with life? Or are we truly alone?
I didn’t have to wait very long for a tantalising clue, because in 1995 the first confirmed exoplanet – a planet orbiting a star other than the Sun – was discovered. Fast forward to 2018, and we have now discovered thousands of exoplanets. We estimate our unexceptional galaxy alone to contain more than several hundred billion exoplanets (!), and we’re even starting to figure out which gases exist in some
of these planets’ atmospheres.
Yet finding exoplanets is really, really difficult. Until 2015 we weren’t even sure what Pluto’s surface looked like, and Pluto is 5000 times closer than the closest possible exoplanet. As exoplanets are almost always too faint and tiny to be seen directly, we have to study them by the changes they cause in their parent stars. These changes can be almost unimaginably subtle: brightness fluctuations of a few parts per million, or velocity ‘wobbles’ of tens of centimetres, on stars many trillions of kilometres away. When you consider that stars themselves are racing through space, pulsating, spinning, violently ejecting hot plasma and more … well, it all gets a bit complicated.
That’s where my own research comes in. I develop and apply tools (physical models, mathematical techniques, computational methods) for detecting and studying the most elusive exoplanets. Inevitably this requires a better understanding of the complexities of their host stars.
In essence, my research aims to discover smaller exoplanets around a wider variety of stars than has previously been possible. Although we have discovered thousands of exoplanets, we’ve not yet managed to discover Earth-sized planets orbiting a comfortable distance from Sun-like stars. Our ideas about our place in the Universe would be profoundly shaken if we could confirm that the cosmos abounds with exoplanets with all the right conditions for life as we know it, to say nothing of life as we don’t know it ...
During my doctoral studies in Oxford, I developed tools that enable astrophysicists better to disentangle stellar signals from those of genuine exoplanets, and I helped discover several new exoplanets. I also proved that what we thought at the time to be the closest exoplanet to Earth – Alpha Cen Bb – actually didn’t exist! But I have little interest in being a ‘planet killer’. I strongly suspect there are many Earth-analogue pale blue dots out there in the vastness of the universe and I very much hope to learn about them in my lifetime.
Besides looking for new planets, I also conduct research on science education. I believe that science, and especially physics, education too often fails to enlighten or inspire students; I am also troubled by the lack of diversity in STEM (science, technology, engineering and mathematics) disciplines.
Outside academia, if I’m not in a dark techno club in Berlin, or curled up with a good book, you can probably find me behind the lens of a camera. In recent years my wife and I have enjoyed creating award-winning photographic accounts of life ‘inside’ or behind the scenes at the University of Oxford, and we hope to find time to expand this project from Oxford to Oxbridge. After all, Cambridge is surely one of the most beautiful and awe-inspiring places on this planet.