Jonathan Fortney

May 24, 2013

I am a planetary scientist that works to understand planets as classes of astrophysical objects. My current research is on modeling planetary atmospheres, interiors, and thermal evolution.

In my work on exoplanets I make connections between these distant planets, which we are just beginning to understand, and our solar system's planets, for which we have abundant data and a long history of research. However, there are classes of planets that astronomers are finding, like "Super Earths," that have no analogue in the solar system! These exciting fields will continue to expand, fueled by ground-based observations, space missions, and new modeling efforts.


My interests include the interiors and atmospheres of planets in and out of the solar system. I work to understand planets as classes of astrophysical objects. Mostly I'm a modeler and theorist, with a few additional observational projects.

Postdocs working with me: Nadine Nettelmann
Grad students working with me: Eric Lopez, Caroline Morley

Former postdocs: Eliza Kempton, Philip Nutzman
Former grad students: Neil Miller, Katie Morzinski

  1. The Kepler Mission. The primary goal of this NASA space telescope is to measure the frequency of Earth-size planets in Earth-like orbits around Sun-like stars. This may be the most important number in the history of astronomy! Over the years I have been a science team member and close collaborator. Often I've been helping to understand what mass and radius measurements tell us about the structure of detected planets, as well as to interpret observations of optical light from the close-in hot Jupiter planets.
  2. Thermal evolution models of extrasolar super Earths, giant planets, Jupiter, and Saturn. What is nature and composition of exoplanets? How do they cool over time and when are they easiest to detect? What is the current distribution of rock, iron, water, and possibly helium in their interiors, and how does this change with time? Do all giant planets possess cores of ice and rock, and what does this tell us about their formation? Can planets be tidally disrupted? There are now known to be hundreds of planets that transit their parent star, allowing us to measure their radii, masses, and densities.
  3. Calculations of the atmospheric structure and spectra of all kinds of planets. How do planetary atmospheres show us their planetary composition? How do planets maintain or lose their atmospheres? What is the day-night temperature contrast of tidally locked planets? What are the main molecular absorbers in these atmospheres? How well can we constrain the chemical abundances of these atmospheres with data from current and future telescopes?
  4. Emission spectra and cloud formation in the coolest brown dwarfs and planets. Astronomers can now find failed stars with temperatures between 500 K and Jupiter's 125 K. We're modeling clouds than range from the exotic (potassium chloride salt) to the common (water) that form in planets and brown dwarfs in this temperature range. I'm a member of the Gemini Planet Imager science team that will begin finding and characterizing cool planets in 2014.

UCSC is a great place for theoretical astrophysics as well as planetary sciences. I am a member of Theoretical Astrophysics Santa Cruz (TASC) as well as the Center for the Origin, Dynamics, and Evolution of Planets (CODEP).


Me speaking with Seth Shostak about exoplanets on Big Picture Science.

Exoplanets at your fingertips!
Download the Kepler Explorer app for iPad and iPhone here! Read the press release here.

"Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity -- in all this vastness -- there is no hint that help will come from elsewhere to save us from ourselves. It is up to us. It's been said that astronomy is a humbling, and I might add, a character-building experience. To my mind, there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly and compassionately with one another and to preserve and cherish that pale blue dot, the only home we've ever known."
--Carl Sagan