extremely tenuous and surface-bound exosphere composed of atoms like sodium and potassium released through processes such as photon-stimulated desorption, micrometeoroid impact vaporization, and solar wind sputtering (Killen et al., 2007). This creates a highly variable and asymmetric exosphere that responds rapidly to solar activity and the position of the planet along its orbit. In contrast, Venus, Earth, and Mars possess exospheres dominated by hydrogen and oxygen, originating from the photodissociation of water vapor, molecular oxygen, and carbon dioxide in their lower atmospheres (Johnson et al., 2008;Sánchez-Cano, 2025;Hunten, 1982). These exospheres are shaped by both thermal (Jeans escape) and non-thermal processes such as charge exchange and dissociative recombination, leading to significant atmospheric escape over geological time (Jakosky et al., 2018;Chaffin et al., 2024). The hydrogen corona of Mars also exhibits strong seasonal and solar cycle variability, as observed by the Hubble Space Telescope (HST) and Mars missions like the Mars Atmosphere Volatile EvolutionN (MAVEN), Mars Express (MEx), and Mars Global Surveyor (MGS), indicating a dynamic coupling between the lower atmosphere, upper atmosphere, and solar forcing (Bhattacharyya et al., 2017;Chaffin et al., 2014;Halekas, 2017;Heavens et al., 2018). The Moon also exhibits a transient exosphere, where species such as argon, helium, and hydrogen are released through radiogenic decay and solar wind interactions, forming a highly time-variable and surface-bound environment (Wilson et al., 2006;Wurz et al., 2007). Hence, the exosphere acts as a sensitive tracer of atmospheric loss, surface composition, and star-planet interactions, making it a key region for understanding long-term planetary evolution with implications that extend beyond our Solar System.A total of 15 individual original research articles were contributed to the research topic entitled "Dynamic Exospheres of Terrestrial Bodies Through the Solar System". In this section, we briefly summarize these articles by grouping them under common scientific themes.A subset of studies in this collection focuses on the large-scale variability of Earth's hydrogen exosphere driven by solar activity. Zoennchen et al. ( 2024) compared three-dimensional hydrogen distributions during solar minimum and solar maximum using TWINS Lyman-α observations, demonstrating significant changes in the density and morphology of the geocorona over the solar cycle. Complementing this, Jung et al. ( 2025) estimated neutral densities near the subsolar region during solar maximum using XMM-Newton soft X-ray observations. These results demonstrate how variations in solar irradiance regulate the global structure and extent of the geocorona.Several papers focus on how exospheric neutrals influence plasma transport and magnetospheric dynamics on Earth. Lin et al. (2024)
Bhattacharyya et al. (Wed,) studied this question.