Colloquium: Laboratory exploration of planetary interiors
Rev. Mod. Phys. 98, 031004 – Published 30 September, 2026
DOI: https://doi.org/10.1103/nft2-txrm
Abstract
Space- and ground-based observatories are discovering exoplanetary systems and new worlds without bound. Understanding the composition, evolution, and implications of these compact objects requires one to unlock the nature of their interiors, where conditions reach millions (hundreds of gigapascals) to billions (hundreds of terapascals) of atmospheres in pressure owing to the crushing influence of gravity. These conditions span from chemical pressures, , where external forces overwhelm chemical forces, to atomic pressures, , which disrupts the shell structure of atoms, to the incipient threshold of thermonuclear fusion at , which is roughly the upper bound interior pressure for giant planets. Understanding matter at such conditions is just now becoming possible with today’s high-energy-density facilities, both high-energy lasers and pulsed-power facilities. Many discoveries have already reshaped our understanding and intuition of extreme matter including the dramatic density-temperature dependence for hydrogen metallization, the phase separation of helium and hydrogen in the deep interior conditions of Jupiter and Saturn, the superionic phases of water and ammonia at the deep interior conditions of Uranus and Neptune, the formation and persistence of diamond upon compression of hydrocarbons, and the melting of to a conducting-polymeric soup making the formation of magma oceans in terrestrial systems possible. This Colloquium describes a suite of laser-induced dynamic compression experiments that are currently underway to characterize the properties of matter under these uncharted extreme conditions together with some unexpected discoveries and planetary implications.
