Sara Seager (born July 21, 1971) is a Canadian-American astronomer and planetary scientist. She is a professor at the Massachusetts Institute of Technology, though she will return to her alma mater the University of Toronto to join the Canadian Institute for Theoretical Astrophysics (CITA) as North Star Distinguished Professor, starting September 1, 2026. Seager is known for her work on extrasolar planets and their atmospheres. She is the author of two textbooks on these topics, and has been recognized for her research by Popular Science, Discover Magazine, Nature, and TIME Magazine. Seager was awarded a MacArthur Fellowship in 2013 citing her theoretical work on detecting chemical signatures on exoplanet atmospheres and developing low-cost space observatories to observe planetary transits.
Background Seager was born in Toronto, Ontario, Canada, and is Jewish. Her father, David Seager, who lost his hair when he was 19 years old, was a pioneer and one of the world's leaders in hair transplantation and the founder of the Seager Hair Transplant Center in Toronto. She earned her BSc degree in mathematics and physics from the University of Toronto in 1994, assisted by a NSERC University Undergraduate Student Research Award, and a PhD in astronomy from Harvard University in 1999. Her doctoral thesis developed theoretical models of atmospheres on extrasolar planets and was supervised by Dimitar Sasselov. She held a postdoctoral research fellow position at the Institute for Advanced Study between 1999 and 2002 and a senior research staff member at the Carnegie Institution of Washington until 2006. She joined the Massachusetts Institute of Technology in January 2007 as an associate professor in both physics and planetary science, was granted tenure in July 2007, and was elevated to full professor in July 2010. As of 2013 she holds the "Class of 1941" chair. She was elected a Legacy Fellow of the American Astronomical Society in 2020.
Personal life She is married to Charles Darrow and they have two sons from her first marriage. Her first spouse, Michael Wevrick, died of cancer in 2011.
Academic research
Seager's research has been primarily directed toward the discovery and analysis of exoplanets; in particular her work is centered around ostensibly rare earth analogs, leading NASA to dub her "an astronomical Indiana Jones." Seager used the term "gas dwarf" for a high-mass super-Earth-type planet composed mainly of hydrogen and helium in an animation of one model of the exoplanet Gliese 581c. The term "gas dwarf" has also been used to refer to planets smaller than gas giants, with thick hydrogen and helium atmospheres. Together with Marc Kuchner, Seager had predicted the existence of carbon planets. Seager has been the chair of the NASA Science and Technology Definition team for a proposed mission, "Starshade", to launch a free-flying occulting disk, used to block the light from a distant star in order for a telescope to be able to resolve the (much dimmer) light from an accompanying exoplanet located in the habitable zone of the star. In years since 2020, Sara has been focusing on work related to Venus, with the potential discovery of phosphine, a biosignature gas, in the upper atmosphere.
Seager equation Seager developed a parallel version of the Drake equation to estimate the number of habitable planets in the Galaxy. Instead of aliens with radio technology, Seager has revised the Drake equation to focus on simply the presence of any alien life detectable from Earth. The equation focuses on the search for planets with biosignature gases, gases produced by life that can accumulate in a planet atmosphere to levels that can be detected with remote space telescopes.
N = N ∗ F Q F HZ F O F L F S {\displaystyle N=N^{*}F_{\text{Q}}F_{\text{HZ}}F_{\text{O}}F_{\text{L}}F_{\text{S}}}
where:
N = the number of planets with detectable signs of life N* = the number of stars observed FQ = the fraction of stars that are quiet FHZ = the fraction of stars with rocky planets in the habitable zone FO = the fraction of stars with observable planets FL = the fraction of planets that have life FS = the fraction of life forms that produce planetary atmospheres with one or more detectable signature gases
Asteria spacecraft Seager was the principal investigator of the Asteria (Arcsecond Space Telescope Enabling Research in Astrophysics) spacecraft, a 6-U cubesat designed to do precision photometry to search for extrasolar planets, a collaborative project between MIT and NASA's Jet Propulsion Laboratory. ASTERIA was launched into low Earth orbit from the International Space Station on November 20, 2017, and successfully operated until its orbital decay on April 24, 2020.
Venus missions
In 2020, Seager led a team proposing a mission Venus Life Finder, a small spacecraft to investigate the possibility of life in the atmosphere of Venus. The mission will be a privately funded spacecraft to be launched by Rocket Lab on the Electron rocket with a target launch date in summer 2026. The Morning Star Missions to Venus team, including Seager, have planned a thorough list of missions with the aim of finding "signs of life or life itself" on Venus. These missions include the Venus Habitability Mission, Rocket Lab Mission to Venus, and Atmospheric Cloud Sample Return Mission. The feasibility of these missions depends on the efficiency of atmospheric data collection, through the direct in-situ examination of collected cloud liquid material, or the sample return of the material with further investigation to be performed on Earth-based laboratories. The proposed instrumentation include cost-effective probes designed to investigate the chemical signatures and will return solid, liquid, and cloud samples from the 48 km to 60 km altitude cloud-decks of Venus. The mission schedule for the Venus Habitability Mission is set with a target launch date of May 2031.
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