Imagining life on other planets is usually the work of science-fiction authors, but increasingly it is becoming the work of current astronomers. Although it had been theorized that there existed other planets outside of our solar system, exoplanets were only confirmed in the late 1980s. The field exploded when the Kepler space telescope started finding thousands of exoplanets. A rich field of study was born.
One of IU’s own astronomers focuses on the interactions of these distant planetary systems. Dr. Songhu Wang became interested in exoplanet research when he was learning about non-linear dynamics in his undergraduate years. He worked with chaos theory, where “if your initial conditions are a little bit different, your results are totally different.” He started out being interested in pure mathematics, but got drawn into the practical aspects of it. Chaos theory can be applied to diverse fields of study like the stock market, weather systems, or even the spread of disease based on the movement of people. Of course, it’s also used in astronomy.
One of the things that fascinates him now is trying to understand what we aren’t seeing. For years, astronomers have only been able to study our own solar system. Before other star systems were discovered, it was assumed that they would look like ours. Astronomers believed that features of our solar system — such as planets smaller than Neptune and larger than Earth do not exist — reflected general truths about the universe. These assumptions were even built into the mathematical models astronomers used to describe and explain planet formation. Yet when the Kepler Space Telescope started returning data, hundreds of exoplanets were discovered that no one thought possible. Dr Wang notes, “we have a lot of expectations for what planets should be, but the universe doesn’t work that way.” It’s something he tries to keep in mind when working. The universe is full of surprises, so sometimes you have to look in unexpected places to find interesting discoveries.
To do this, he conducts a lot of observational research. While this sometimes means travelling to a telescope like the Palomar observatory in California, he also works with automatic telescopes (like the APF telescope) that don’t require astronomers to stay up all night. This frees him to do his other work as a faculty member. Between teaching prep, meetings, and department talks, it can be a balancing act to keep everything on track. Through it all, he has one strong guiding principle: “I work a lot, but I spend more time thinking. That’s more important than just doing things.”
This thinking time includes managing the students who do research with him to make sure they are growing as scientists and progressing on their projects. It is also including time invested considering the instruments here at IU and figuring out how to use them to do research in a way no other instruments can do. And some of his time is spent trying to find the right question. “There’s always something with a 100 sigma detection [a detection with no ambiguity] that no one noticed,” he told me. Hidden in the data of a research project looking for one answer, lurks a clear answer to a question no one has asked yet. Those answers are often the discoveries that change the way we think about the universe.
Looking to the future, I asked him what he thinks will be the big news story of 2030. It’s a difficult question in a field that has been changing so rapidly. In 2010, there had not yet been any data returned from the Kepler space telescope, which radicalized our understanding of planets. “Every 10 years, new things are discovered and totally blow our minds.” When pressed, he looked to the new instruments. Long term studies like Gaia will help us to discover planets with longer orbits. New telescopes like JWST should have the sensitivity to study the detailed atmospheric properties of exoplanets and perhaps even take direct images of some small planets. If we’re really lucky, there will be progress in studying exomoons with ESO’s PLATO mission.
Still, these are all guesses. Some groundbreaking discoveries appear obvious in hindsight, but to find them, scientists had to look beyond their expectations — a deceptively difficult achievement. “That’s maybe the most important question,” he reflected. There may be other discoveries like that of 51 Pegasi b just waiting for us. Scientifically, it is significant, and it doesn’t even require brand new technology to find. The data was there, but no one noticed it. What else is hiding in plain sight, waiting to be found some day in the future? It’s something he asks himself every day.