Studying the Mysteries of the Outer Solar System

In 2012 I was awarded a Royal Society University Research Fellowship (URF), to continue my research at Oxford.  Part of the application process is to write a simple overview of the work I intend to accomplish, and I've decided to publish it here as a general introduction to my giant planet research.

Exploring the Mysteries of the Giant Planets in our Solar System and Beyond

The frigid outer reaches of our solar system is the realm of the giants.  Four enormous balls of gas and ice move slowly along their orbits, taking decades to complete one lap of the Sun.  Observations of these worlds with telescopes and robotic spacecraft reveal incredibly dynamic planets, with alien weather systems in churning atmospheres, spectacular storms larger than our entire planet and a diverse range of cloud colours.  The giant planets are a paradise for planetary scientists who seek to understand the atmospheric physics and chemistry at work throughout our solar system, in the hope that we might better understand our own terrestrial atmosphere and the emergence of life.  Furthermore, the giant planets contain in their compositional make-up a unique record of the solar system’s early history, as the dust, ice and gas that collapsed to form the planets billions of years ago is forever stored within their churning atmospheres.

I use powerful ground-based and space-borne telescopes to study these worlds, in addition to the most sophisticated interplanetary spacecraft ever built, Cassini, which is orbiting Saturn and returning spectacular images from a billion kilometres away.  Our exploration of the outer solar system is still in its infancy, and yet our understanding is being used to interpret the very first studies of planets around other stars (exoplanets).  There’s an enormous potential for new discoveries at the cutting edge of planetary astronomy: what might these places be like, and is the structure of our solar system (habitable worlds in the inner system and cold giants in the outer system) commonplace?  These questions go to the very heart of modern planetary science, and our quest to understand the bewildering array of atmospheres in our galaxy.  

The research I propose will address two connected questions – how and why do the giant planets vary in their appearance (i.e., what drives the huge storms that we see, with their changing colours, clouds and temperatures); and what can the chemical composition of these worlds tell us about their origins, both in our solar system and around other stars?  I’ll be using data from a variety of sources, from observatories in Hawaii and Chile, to telescopes in Earth orbit and the Cassini spacecraft at Saturn.  Computer models will replicate the spectrum of light observed from each planet, and allow us to measure the temperature, gaseous composition and clouds within their atmospheres.  Ultimately I want to answer these questions by designing new exploration missions here in the UK, to fire the imaginations of the next generation of scientists and engineers. 

The presence of an atmosphere around our planet, protecting us from solar radiation and keeping the temperatures in the habitable range, was essential for the development of life.  The immense gravity of the giants shields our world from catastrophic impacts with solar system debris.  By understanding how this planetary system formed and how atmospheres evolve and change at different distances from the Sun, I hope to gain a better understanding of the origin of Earth and its protective atmosphere.   If we can understand our own origins, this will be a step towards answering the ultimate question for planetary science – are habitable terrestrial environments common in our galaxy, or are we alone?