Clara Sousa-Silva

Sousa-Silva earned an integrated MPhys at the University of Edinburgh and a PhD at University College London.⁠[1]

Her doctoral work at UCL simulated the spectrum of phosphine; her thesis, Modelling phosphine spectra for the atmospheric characterization of cool stars and exoplanets, was completed in 2015.⁠[2]

She was Educational Co-ordinator for the Twinkle Space Mission, whose work includes the ORBYTS program.⁠[3]

ORBYTS (Original Research By Young Twinkle Scientists) pairs researchers with secondary schools, which they visit fortnightly so pupils can contribute to publishable research; in the 2017–2018 academic year it had 14 researcher-school partnerships and about 100 pupils.⁠[4]

In March 2019 the Heising-Simons Foundation selected Sousa-Silva, then a postdoc in MIT’s Department of Earth, Atmospheric and Planetary Sciences, as a 51 Pegasi b Fellow; she had developed RASCALL, a method for rapidly simulating molecular spectra, planned to expand her public spectral database to 16,000 molecules and would keep working with Sara SeagerSara SeagerSara Seager is a Canadian-American astrophysicist and planetary scientist who taught for many years at MIT; a pioneer of the study of exoplanet atmospheres, she has worked on space missions such as TESS and leads efforts to look for signs of life on Venus, and she received the 2024 Kavli Prize in Astrophysics.Open the full entry’s biosignatures group.⁠[5]

On December 18, 2019, MIT described her first-author paper in Astrobiology: on Earth phosphine is associated only with anaerobic life, and if a rocky exoplanet held phosphine in amounts similar to Earth’s methane, a telescope such as the James Webb Space Telescope could detect it from as far as 16 light years, which would be a clear sign of life.⁠[6]

On September 14, 2020, a Jane Greaves–led team, Sousa-Silva among them, announced phosphine in Venus’s clouds in Nature Astronomy.⁠[7]

In October 2020 reanalyses of the Venus data by other scientists questioned the signal; Sousa-Silva, then at the HarvardHarvard UniversityHarvard University is a private research university in Massachusetts, established by the Massachusetts Bay Colony legislature in 1636 and named in 1639 for early benefactor John Harvard. Its principal campuses are in Cambridge and the Allston and Longwood neighborhoods of Boston. It includes Harvard College, graduate and professional schools, and the Radcliffe Institute for Advanced Study. Two governing boards share oversight. Alan M. Garber was president as of October 2026, and the endowment stood at $56.9 billion at the end of fiscal 2025.Open the full entry-Smithsonian Center for Astrophysics, said, “This is normal. This is what science looks like.”⁠[8]

The detection and its interpretation as a sign of life were later called into question, including by Sousa-Silva herself, but the episode led scientists to study phosphine and its possible abiotic sources more seriously.⁠[2]

In June 2021 she appeared, as a quantum astrochemist at Harvard, on episode 195 of the Lex FridmanLex FridmanLex Fridman is a Soviet-born, US-raised computer scientist and podcast host who works as an MIT research scientist on human-AI interaction and autonomous driving. His Lex Fridman Podcast is known for hours-long conversations with guests including heads of state and technology leaders.Open the full entry Podcast, on searching for signs of life on Venus and other planets, with segments on the discovery of phosphine on Venus, molecular fingerprints, biosignature gases and alien civilizations.⁠[9]

In July 2021 she gave the talk “The fingerprints of life beyond Earth” at TEDMonterey, making the case for a new way to seek habitable planets and describing her research on phosphine, a poisonous molecule that might signal life beyond Earth.⁠[10]

She spent three years as a postdoctoral associate at MIT and then became a 51 Pegasi b Fellow at the Harvard & Smithsonian Center for Astrophysics.⁠[3]

In 2022 she joined Bard College as assistant professor of physics; she had been offered a Sagan Fellowship, which she declined, and had directed the Science Research Mentoring Program at the Center for Astrophysics and MIT.⁠[1]

In August 2023 Bard College received $124,936 from the Heising-Simons Foundation for a five-year project led by her to simulate and detect potential biosignatures from exoplanets.⁠[11]

On November 16, 2023, she gave the Space Talk “Alien Life and How to Find It” at Liberty Science Center, as an assistant professor of physics at Bard College and a researcher at the Institute of Astrophysics and Space Sciences.⁠[12]

On April 19, 2024, she gave a physics colloquium at Kenyon College titled “The Fingerprints of Life Beyond Earth,” on combining organic chemistry and quantum mechanics to interpret astrophysical signals and ultimately detect life on an exoplanet.⁠[13]

In 2025 she and colleagues published a paper in Science reporting phosphine in the atmosphere of a brown dwarf; she said that detecting phosphine where life cannot exist is a critical piece of the puzzle for understanding its meaning in potentially habitable environments.⁠[14]

The study, led by Adam Burgasser of UC San Diego, used the James Webb Space Telescope to find phosphine in the atmosphere of the ancient brown dwarf Wolf 1130C, although the gas had been missing from other similar objects.⁠[15]

Personal website: Public link: https://clarasousasilva.com (opens in a new window)⁠[9]

X: Public account: https://x.com/drphosphine (opens in a new window)⁠[9]