Overview
How can we discover what makes a planet habitable, by learning how it can become uninhabitable? My research uses models of planetary interiors and atmospheres to trace how planets evolve toward, or away from, habitable conditions, from abiotic ozone in Venus' atmosphere to sub-Neptunes whose magma oceans never solidify. I am currently developing an end-to-end modelling pipeline to compare my models to observations of sub-Neptune atmospheres. Looking ahead, I want to fold cloud and haze physics into these models, sharpening the tools needed to interpret the next generation of habitability missions.
Selected papers
Calder, R., Shorttle, O., Nicholls, H., Lichtenberg, T., & Guimond, C. M. (2026). Most rocky sub-Neptunes are molten: mapping the solidification shoreline for gas dwarf exoplanets. Monthly Notices of the Royal Astronomical Society, 549(3), stag1007. (link)
Calder, R., Shorttle, O., Jordan, S., Rimmer, P., & Constantinou, T. (2025). Abiotic ozone in the observable atmospheres of Venus and Venus-like exoplanets. Monthly Notices of the Royal Astronomical Society, 540(3), 2432-2450. (link)
Nicholls, H., Lichtenberg, T., Riegler, B., Calder, R., & Fortuin, V. (2026). Constraining the lives and times of exoplanets through evolutionary Bayesian retrievals. arXiv preprint arXiv:2607.25845. (link)
Career
PhD in Astronomy: Institute of Astronomy, University of Cambridge (2023-present)
Part II supervisor: Institute of Astronomy, University of Cambridge (2023-present)
MPhys Astrophysics: University of St Andrews (2018-2023)
Qualifications
MPhys Astrophysics: University of St Andrews, Graduated with First Class Honours
Awards and Prizes
2023 - Class Medal, University of St Andrews, for highest graded student in Masters (MPhys) year
2021-2022 - Laidlaw Leadership and Research Scholarship, University of St Andrews, involving an undergraduate project with the University of St Andrews and a Leadership in Action project with the Laidlaw Foundation
2018-2023 - Deans Scholar, University of St Andrews
Teaching
Undergraduate Supervisor - Directed sessions involving 2-3 students to help them consolidate material covered in lectures. Marked submitted worksheets and past paper questions:
- 1st Year: Topics in Astrophysics (3rd Year Undergraduate Course): 9 students, 12 sessions
- 2nd Year: Topics in Astrophysics (3rd Year Undergraduate Course): 4 students, 8 sessions
Outreach
Public Lectures and Stargazing - Gave lectures to members of the public explaining current science and led supervised star-gazing sessions for members of the public:
◦ 21/10/2024: Barrington Scout Group
◦ 22/11/2024: 6th/17th Cambridge Scouts
◦ 17/02/2025: 50th Cambridge Cub Scouts
◦ 18/02/2025: Team Consulting
International Women’s Day Committee (2025) - Participated in the International Women’s Day committee. This committee organised various department activities with the aim of celebrating female astronomers and promoting gender diversity in the field of astronomy.
◦ Lead and organised a workshop for local secondary school children to teach them about exoplanet transits and famous female astrophysicists in the field of exoplanets.
◦ Helped run the International Women’s Day stall at the Institute of Astronomy Open Day.
◦ Gave a lecture at the Institute of Astronomy Open Day about famous female astrophysicists in the field of exoplanets.
