Simon Lock

Simon J. Lock

Planetary Science Option Postdoc

Division of Geological and Planetary Sciences

California Institute of Technology



My research lies at the boundary between the fields of astrophysics, planetary science, geophysics and geochemistry. I study the formation, structure and evolution of terrestrial and giant planets. In particular, I aim to elucidate the history of Earth and how it became habitable. More...

What's New?

AGU 2020

Please tune in to my talk (DI022-01 A tectonically active early Earth driven by the tidal recession of the Moon) at this years AGU. The closed captioning has some significant (if amusing) errors so here is a transcript of my talk. Video and slides may follow soon.

New paper on visualization of astrophysical data

A new paper led by University of Illinois graduate student Pat Aleo is out in Astronomy and Computing. The paper describes a new pipeline for producing physically-meaningful cinematic visualizations of astrophysical simulations using terrestrial synestias as an example. All the tools are available for you to try your own visualizations at home! A preprint of the accepted manuscript is available here.

New paper in Space Science Reviews

A new collaborative paper is out in Space Science Reviews! This was the result of the ISSI Europlanet Workshop "Reading Terrestrial Planet Evolution in Isotopes and Element Measurements" held in October 2018 in Bern, Switzerland. The paper discusses geodynamical models of lunar origin in light of geochemical constraints from lunar and terrestrial rocks. A preprint of the accepted manuscript is available here.

The energy budget during and after giant impacts

We have published two new studies looking at the energy budget during giant impacts (Carter et al., accepted) and how the energy budget and shape of post-impacts planets change as they recover after impacts (Lock et al., 2020). We find that changes in kinetic, potential and internal energy are all significant with implications for the structure of post-impact bodies, the early evolution of Earth and the dynamics of lunar tidal recession.

Pressures after giant impacts

We have published a new study showing that the pressures in bodies after giant impacts can be less than half what had been expected, changing the interpretation of the geochemical tracers of accretion. Pressures increase after impacts as the body cools and satelites tidally receed, driving a number of previously unrecognized processes.

Caltech press release

Open access paper

Pellas-Ryder award

I have been award the Pellas-Ryder award! Jointly awarded by the Meteoritical Society and the Planetary Division of the Geological Society of America, this award is conveyed for the best planetary science paper written by an undergraduate or graduate student and published during the previous year. The award recognizes my work on lunar origin which was published in Lock et al. (2018). See citation here.

Colloquium at the Carnegie Institute

I recently gave a seminar at the Geophysical Laboratory at the Carnegie Institute. You can find a link to a video of the presentation here.

New Adler Planetarium show

Adler Planetarium in Chicago has developed a new show, 'Imagine the Moon', that 'explores how the Moon has inspired human creativity, learning, and exploration ever since we have looked to the sky'. This show features some amazing animations of our recently proposed Moon model, created with input from Sarah Stewart and myself.

Sarah Stewart is a genius

Congratulations to my former Ph.D advisor, Sarah Stewart, for being selected as a MacArthur Fellow. This award is commonly known as the 'genius grant'.

Origin of the Moon

We have proposed a new model for the origin of the Moon: that the Moon formed inside the vaporized Earth. Our model can explain various observations of Earth and the Moon for the first time. Learn more...

UC Davis press release

Harvard Gazette

Journal article

Preprint on arXiv

A new astrophysical structure

We have discovered a completely new type of astrophysical object that we have named synestias. These are fascinating objects that have the potential to revolutionize our understanding of how planets form and evolve. Intrigued? Learn more...

UC Davis podcast

UC Davis press release

AGU press release

Journal article

ArXiv pre-print


Contact Information


slock {at} caltech {dot} edu


(617) 520-4813 (Google Voice)

(626) 395-3296 (Office)


Division of Geological and Planetary Sciences
California Institute of Technology
1200 East California Boulevard
CA 91125


All photos used on this site are either available under a creative commons license, or are the property of Brian Lock or NASA.