Cosmic shoreline

Bodies plotted by insolation and escape velocity form a rough boundary known as the "cosmic shoreline".

The cosmic shoreline is a concept in planetary science that describes an empirical boundary between planetary bodies that are able to retain significant atmosphere and those that cannot. The concept compares a planet's escape velocity with its insolation (energy received by the planet from its local star). When planets and moons in our Solar System are plotted in accordance with these two parameters, objects with thick atmospheres (such as Saturn and Jupiter) appear on one side, while airless planets with no (or very little) atmosphere appear on the other, forming a rough dividing line known as the "shoreline". ^{[1] [2] [3] [4]}

References

1. Zahnle, K. J.; Catling, D. C. (March 2013). "The Cosmic Shoreline" (PDF). 44th Lunar and Planetary Science Conference.
2. "Oceans, Beaches, Cosmic Shorelines: Our Changing Views of Habitable Planets - NASA Science". 2019-06-18. Retrieved 2026-03-11.
3. Zahnle, Kevin J.; Catling, David C. (2017-07-10). "The Cosmic Shoreline: The Evidence that Escape Determines which Planets Have Atmospheres, and what this May Mean for Proxima Centauri B". The Astrophysical Journal. 843 (2): 122. doi:10.3847/1538-4357/aa7846. ISSN   0004-637X.
4. Ji, Xuan; Chatterjee, Richard D.; Coy, Brandon Park; Kite, Edwin S. (2025-10-15), The Cosmic Shoreline Revisited: A Metric for Atmospheric Retention Informed by Hydrodynamic Escape, arXiv, doi:10.48550/arXiv.2504.19872, arXiv:2504.19872, retrieved 2026-03-11