Cosmic shoreline
The term cosmic shoreline is a metaphor used by Astronomers to categorize rocky planets, over whether it is likely they have an atmosphere, that can harbor life, like that on the surface of Planet Earth.[1][2][3][4]
Several factors influence whether a planet retains an atmosphere, including the average temperture of its surface; its instellation -- how much light falls on it; its surface gravity; and whether it orbits an active star, subject to frequent , violent stellar flares.[1]
Planets on the boundary of whether they are likely to have an atmosphere are considered to be on the cosmic shoreline. Planet Mars, for instance, is close to the line as to whether it can retain an atmosphere.[1]
References
[edit | edit source]- ↑ 1.0 1.1 1.2
David Kipping (2026-05-23). "We're Finally Unlocking the "Cosmic Shoreline"". Cool Worlds. Retrieved 2026-07-15 – via YouTube.
Head to an exoplanet seminar or conference and you'll constantly hear astronomers talking about "the Cosmic Shoreline". But - what the heck is that? Why is it so important?
- ↑
Pat Brennan (2019-06-18). "Oceans, Beaches, Cosmic Shorelines: Our Changing Views of Habitable Planets". NASA Science. Archived from the original on 2024-05-21. Retrieved 2026-07-15.
And as we sail this sea of unfamiliar planets, we finally fetch up on the cosmic shoreline. The shoreline is metaphorical, but might be a very real statistical trend that links all planets – those in our solar system and the exoplanets around other stars.
- ↑
Keith Cowing (June 23, 2026). "An Empirical Determination Of The Cosmic Shoreline". Astrobiology magazine. Retrieved 2026-07-15.
The cosmic shoreline concept was introduced to separate planets with atmospheres from those without, by relating the cumulative X-ray and extreme-ultraviolet (XUV) instellation (integrated over the planet’s lifetime) to the planetary escape velocity, using the Solar System planets to anchor the empirical relation.
- ↑ "The Cosmic Shoreline and the Atmospheres of Red Dwarf Planets". Kyplanet. 2025-10-11. Archived from the original on 2026-06-13. Retrieved 2026-07-15 – via YouTube.