Jupiter’s X-ray emissions and prospects for soft X-ray imaging

Abstract

X-ray observations of the Jovian system have greatly advanced our understanding of giant-planet magnetospheres and their coupling to moons, plasma sources, and the solar wind. Over four decades of measurements have revealed diverse X-ray emissions originating from Jupiter’s aurorae, disk, the Io plasma torus, the surfaces of its moons, and the radiation belt. Among these, the aurora remains the most luminous source, with soft X-rays produced primarily by charge exchange between highly charged heavy ions and Jupiter’s upper atmosphere, and hard X-rays generated through electron bremsstrahlung. Recent discoveries, including quasi-periodic pulsations, dawn-storm-related enhancements, and hemispheric asymmetries, highlight the complex interplay among internal magnetospheric processes, Io-driven mass loading, and variable solar wind conditions. Meanwhile, rapid developments in soft X-ray imaging technologies, particularly wide-field lobster-eye optics and radiation-tolerant CMOS detectors, offer new opportunities for global, time-resolved studies of Jupiter’s magnetosphere based on close-range imaging missions. Such instruments could, for the first time, capture continuous X-ray images of the auroral regions, the Io plasma torus, and Galilean moons, enabling major progress on long-standing questions concerning particle acceleration, plasma transport, and moon-magnetosphere interactions. This review synthesizes the current understanding of Jovian X-ray emissions, highlights key open problems, and outlines the scientific potential of future soft X-ray planetary missions.