Planetärslut

Planetärslut is a term used in speculative discourse and occasional academic writing to denote a theoretical end state of a planetary system or of planetary habitability. Derived from the Swedish elements planetär (planetary) and slut (end), the expression conveys the idea of a final phase, when planetary conditions become inhospitable or the system’s structure undergoes irreversible change.

In astrophysical contexts, planetärslut describes the long-term fate of planets as a star leaves the main sequence. As a sunlike star expands into a red giant, inner planets may be engulfed and outer planets may have their orbits destabilized, potentially ejecting some planets or leaving the system in a new configuration. Remnant white dwarfs may preserve a few survivors while others are lost. The term is not a formal category in planetary science but is used informally to summarize endpoint scenarios studied in celestial mechanics and stellar evolution.

In speculative literature and future-oriented discussions, planetärslut also refers to potential anthropogenic or civilizational endpoints on a planet, such as ecological collapse, irreversible resource depletion, or global catastrophe, after which planetary-scale life support or civilization-level activity ceases or is permanently transformed. In this usage, it serves as shorthand for questions about how long planetary-scale endeavors can endure under various risk factors.

Related topics include planetary habitability, stellar evolution, planetary system dynamics, and existential risk.