Joey Murphy

Exoplanets—planets orbiting stars other than the Sun—are ubiquitous in the Milky Way Galaxy. Using telescopes both on the ground and in space, we can precisely measure their fundamental physical properties. Building up a library of well-characterized exoplanets is key to better understanding how planets form, evolve, and foster life.

Since the discovery of 51 Pegasi b three decades ago, we’ve learned that our galaxy is teeming with exoplanets, or, planets orbiting stars other than the Sun. This revelation has opened new frontiers in observational astronomy, planet formation and evolution theory, and the search for extraterrestrial life. Over the last 15 years, the transit and radial velocity methods have served as the workhorse techniques for exoplanet discovery and characterization. By analyzing an exoplanet’s transit—the periodic decrease in the light from the host star as the planet passes in front—we can measure the planet’s size and orbital properties. By measuring the size of the oscillation of the host star’s radial velocity due to the planet, we can derive the planet’s mass. By combining both measurements, we set the stage for space-based telescopes like JWST to probe the chemical composition of the planet’s atmosphere—observations which can then be interrogated for signs of biological life. In short, the discovery and precise characterization of a library of planets amenable to atmospheric observations is our most expedient path toward finding life among the stars.