Until recently, the planets in our Solar System were all that were known, but through a variety of observational techniques, we now know of 759 extrasolar planets orbiting around other stars. Many of these are massive gaseous planets that resemble Jupiter, but many of these exoplanets are much closer to the star (a fraction of an Earth-Sun distance) than Jupiter is. Their proximity to their host stars induces very high surface temperatures for these stars, and the short orbital periods suggest that the same side of the planet always faces the star. In 2007, Knutson used infrared observations of a particular hot Jupiter, HD 189733b, to establish a difference in temperature between the side facing the star and that hidden from the star, finding that the hot side is 1200 K while the cool side is 1000 K. The relatively small temperature difference suggests that heat is efficiently redistributed in the atmosphere, and this has important implications for models of hot Jupiter atmospheres.
More generally, Knutson's work uses observations of a variety of systems where the planet (which is extremely faint relative to the star) eclipses the star to infer properties about the planets, their atmospheres, and their chemical compositions. By studying the diversity of phenomena in extrasolar planetary systems, Knutson hopes to learn more about the formation of solar systems, including our own, and shed light on the workings of planetary atmospheres.
After graduating from Johns Hopkins in 2004, Knutson moved to graduate school at Harvard where she earned a PhD in astronomy in 2009. From 2009--2011 she was a Miller Fellow at the University of California Berkeley. In 2011 she began as an Assistant Professor in the Division of Geological and Planetary Sciences at the California Institute of Technology.
Previous winners of the Annie Jump Cannon award with JHU connections include Rosemary Wyse (1986), Meg Urry (1990), Annette Ferguson (2003), and Ann Hornschemeier (2007).