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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2603.29700 |
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Table of Contents:
- We report the first unambiguous detection of cannabinoid molecules in an exoplanetary atmosphere. Using 420 hours of JWST observations combining NIRSpec and MIRI instruments, we identify spectroscopic signatures of tetrahydrocannabinol (THC; $Δ^9$-C$_{21}$H$_{30}$O$_2$) and cannabidiol (CBD; C$_{21}$H$_{30}$O$_2$) in the transmission spectrum of the temperate sub-Neptune K2-18b. The THC feature at 2.42~$μ$m is detected at 9.2$σ$ significance, while CBD absorption at 3.69~$μ$m reaches 7.8$σ$. We additionally report a mysterious feature at exactly 4.20~$μ$m detected at 4.20$σ$ (the probability of this coincidence is discussed extensively). Our atmospheric retrievals using the novel \texttt{TerpeneRetrieval} code indicate a CBD-to-THC ratio of 0.40$\pm$0.08, classifying K2-18b as a ``balanced hybrid'' world according to standard terrestrial cannabis taxonomy. We introduce the Cannabis Habitable Zone (``Green Zone'') framework and demonstrate that K2-18b lies squarely within it. We explore multiple production mechanisms including biogenic synthesis, abiotic photochemistry, exogenous delivery via ``space nuggets,'' and deliberate atmospheric engineering by an advanced civilization. These findings suggest that K2-18b may host conditions suitable for advanced photochemistry, atmospheric relaxation processes, and possibly the most chill civilization in the galaxy. If confirmed by independent observations, this represents a paradigm shift in our understanding of biosignatures and the prevalence of recreational organic chemistry in the cosmos.