Katherine de Kleer

She received bachelor’s degrees in mathematics and physics from the Massachusetts Institute of Technology in 2009 and went on to doctoral studies in astrophysics at the University of California, BerkeleyUniversity of California, BerkeleyThe University of California, Berkeley (UC Berkeley) is a campus of the University of California system; the University of California was founded in 1868 through a merger of two institutions and moved to Berkeley, California, in 1873.Open the full entry.⁠[1]

With collaborators she used the Gemini North near-infrared imager and adaptive optics to follow one of the brightest volcanic eruption sequences ever seen in the solar system, on Io, recording its decline over nearly two weeks; the eruptions had been unexpectedly detected by team member Imke de Pater.⁠[2]

From August 2013 to the end of 2015 she led observations with adaptive optics on Keck II and Gemini North, imaging Io on 100 nights and tracking 48 volcanic hot spots; every short-lived intense eruption occurred on Io’s trailing hemisphere.⁠[3]

She and her advisor Imke de Pater presented the results on October 20, 2016, at the joint meeting of the American Astronomical Society’s Division for Planetary Sciences and the European Planetary Science Congress; she noted that some eruptions appeared to trigger one another 500 kilometers apart.⁠[4]

In 2017 she earned her PhD in astrophysics from UC Berkeley and moved to Caltech as a Heising-Simons Foundation 51 Pegasi b Postdoctoral Fellow, joining the Caltech faculty in 2019.⁠[1]

Her research group studies the surfaces, atmospheres and thermochemical histories of solar system bodies through observational signatures at optical, infrared and radio wavelengths, with topics including the Galilean satellites, Io’s volcanism and tidal heating, planetesimal heating and differentiation, and seasonal changes in planetary and satellite atmospheres.⁠[5]

As lead author of a Nature paper, she used Europa’s passage in front of Io on March 8, 2015, observed interferometrically with the twin mirrors of the Large Binocular Telescope, to produce a detailed thermal map of Loki Patera, Io’s largest volcanic crater, revealing two resurfacing waves sweeping around it at different rates.⁠[6]

She appeared on episode 184 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 as a professor of planetary science and astronomy at Caltech, discussing Pluto and the Kuiper belt, Io’s volcanoes, possible life in Europa’s ocean, Venus and Mars, asteroid impact risks and the interstellar object Oumuamua.⁠[7]

As lead author of a Planetary Science Journal paper, she used the Atacama Large Millimeter/submillimeter Array to map the millimeter-wavelength thermal emission of the asteroid Psyche at 30-kilometer resolution, producing the first temperature map of the object, a NASANASAThe National Aeronautics and Space Administration (NASA) is the U.S. federal agency responsible for the civilian space program, aeronautics research and space science. Established by law in 1958 and headquartered in Washington, D.C., it has run programs including Mercury, the Apollo Moon landings, the Space Shuttle, the International Space Station and Artemis.Open the full entry mission target thought by some to be a fragment of a protoplanet’s core.⁠[8]

Since 2022 she has been a Hufstedler Family Scholar at Caltech; her research interests span planetary astronomy, planetary atmospheres, planetary geosciences and planetary surfaces.⁠[9]

A team led by Caltech and Boston University observed the Galilean moons in Jupiter’s shadow and found that all four show oxygen aurorae like those near Earth’s poles, with red light glowing nearly 15 times brighter than green; she was lead author of the paper on the aurorae of Europa, Ganymede and Callisto and said molecular oxygen is likely the main constituent of the icy moons’ atmospheres.⁠[10]

On April 18, 2024, she published a Science paper as first author that used sulfur isotopes in Io’s atmosphere to conclude that Io, Europa and Ganymede entered their Laplace orbital resonance soon after forming and that Io has been volcanically active for billions of years.⁠[11]

The team used ALMA in Chile to find that Io’s atmosphere has a higher sulfur-34 to sulfur-32 ratio than any other measured body in the solar system; geochemical modeling showed that Io may once have lost sulfur at up to five times today’s rate.⁠[12]

In August 2024 Caltech announced that she had received the 2024 Harold C. Urey Prize of the American Astronomical Society’s Division for Planetary Sciences, which recognizes outstanding early-career planetary scientists; that year she was also named a Cottrell Scholar by the Research Corporation for Science Advancement.⁠[13]

Caltech notes that her outreach has included teaching physics classes at San Quentin Rehabilitation Center and serving as an astronomer in residence at Grand Canyon National Park.⁠[13]

In a first-authored abstract for the EPSC-DPS 2025 joint meeting, she and colleagues presented James Webb Space Telescope MIRI/MRS spectra of 14 main-belt asteroids over 5–25 microns, indicating that these asteroids, tens of kilometers across, are covered by a very fine, highly porous regolith layer.⁠[14]

She was an assistant professor at Caltech from 2019 to 2026 and became professor of planetary science and astronomy in 2026.⁠[9]

Personal website: Public link: https://web.gps.caltech.edu/~dekleer/ (opens in a new window)⁠[7]

California Institute of Technology: Official website: https://www.caltech.edu/ (opens in a new window)⁠[5]