Hannah Sanderson

Hannah Sanderson


Current Research

I am working with James Bryson and Claire Nichols on magnetic field generation in rocky bodies (planets, moons and asteroids). Although magnetic fields appear to have been generated by a diverse range of planetary bodies in the past, only three known rocky bodies in our solar system (Earth, Mercury and Ganymede) produce active fields today. Even for the Earth, we have many unanswered questions. We know the current magnetic field of the Earth is powered by light elements being expelled from the growing inner core. However, we still don’t understand how the geodynamo was generated before the solidification of the inner core around 1 billion years ago.

Specifically, I am investigating mechanisms of top-down crystallisation (when the core starts to solidify from the core-mantle-boundary) and their effects on dynamo generation. I want to understand how this applies to a wide-range of rocky body sizes, from small asteroids to moons and planets. My research consists of a combination of analytical work and computer modelling.

I am funded by NERC as part of the Oxford DTP in Environmental Research.


Hannah Sanderson, Amy Bonsor, Alexander Mustill, Can Gaia find planets around white dwarfs?, Monthly Notices of the Royal Astronomical Society, Volume 517, Issue 4, December 2022, Pages 5835–5852, https://doi.org/10.1093/mnras/stac2867

H Sanderson, M Jardine, A Collier Cameron, J Morin, J-F Donati, Can scallop-shell stars trap dust in their magnetic fields?, Monthly Notices of the Royal Astronomical Society, 2022;, stac3302, https://doi.org/10.1093/mnras/stac3302


I obtained my integrated master’s in Natural Sciences, specialising in Astrophysics, from the University of Cambridge in 2021.

For my master’s thesis, I worked with Amy Bonsor to investigate whether the Gaia telescope could find planets around white dwarfs. This involved examining the effects of post-main-sequence stellar evolution on planetary systems, running N-body simulations of planetary systems and understanding the sensitivity of the astrometric detection method.

Black background with 230,000 white dwarfs in an ellipse

All-sky view showing the position and brightness of some 230 000 white dwarfs discovered with ESA’s Gaia satellite. Copyright: ESA/Gaia/DPAC

One of my other areas of interest is stellar magnetic fields and I was able to explore this in the summer of my third year of my undergraduate degree on a summer research placement. I collaborated with Moira Jardine at the University of St Andrews to investigate whether dust in magnetic stable points in M dwarf coronae could explain the “scallop-shell” phenomenon observed in some M dwarfs. You can read more about my experience on the placement here.

Star with magnetic field lines and prominences with comets coming towards is

Prominences are regions ionised hydrogen trapped in magnetic field lines and are the orange regions in this figure. Dust can also be trapped in the field lines and may be delivered by comets/small bodies in the stellar system. This trapped dust can cause dips in stellar flux. Credit: Rose Waugh (@astrophys_rose), University of St Andrews

Other activities

Equality, Equity, Diversity and Inclusivity (EEDI)

LGBTQ+ affinity group logo

I am a postgraduate rep on the department EEDI committee. I am also one of the leaders of the department’s LGBTQ+ affinity group. The idea of the affinity group is to provide a safe space for the LGBTQIA+ members of the department to find community and solidarity in a relaxed space. We run monthly events, including relaxed lunches, ice-cream trips and talk screenings.


At Oxford, I am involved in outreach for the Physics and the Earth Sciences departments. I have taught mock tutorials on the Physics UNIQ Summer School and for Exeter and Queens College. I have been involved in Marie Curious events and have developed a workshop on planetary interiors for Year 5-6 students. If you want me to come deliver a workshop at your school – get in touch!

a line of a paper planetary system lying on the carpet with a person kneeling next to it. There is a Sun, followed by a red magma planet, a tidally locked planet which is read on one side and blue on the other. Then a brown rocky planet, a piece of paper representing the snow line and then a white icy planet.

I also did a lot of outreach as an undergraduate. I was Chair of the Cambridge University Astronomical Society (CUAS)  and organised talks on all areas of Astrophysics as well as helping run observing evenings using the telescopes at the Institute of Astronomy. I was also a member of Cambridge Hands On Science (CHaOS), which involved visits to primary and secondary schools to demonstrate exciting, interactive experiments to help students engage with science.


I teach tutorials for first year Mathematics for Earth Sciences and third year Vector Calculus.