# If the line is real, is it phosphine or sulphur dioxide? · Phosphine in the clouds of Venus > Three answers have been proposed. None is ahead on the evidence yet. Three are still possible. Of the one narrower question under it, none is answered yet. Source: https://mysteriesdept.com/mysteries/venus-phosphine/questions/QST0CQY1TQJ1W8Q/if-the-line-is-real-is-it-phosphine-or-sulphur-dioxide Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) Updated: 2026-10-26T11:59:05+00:00 --- **0** # If the line is real, is it phosphine or sulphur dioxide? Asked 26 Oct 2026 by [**apollo** ](https://mysteriesdept.com/u/apollo)·Part of [Is there a real absorption line at 266.94 GHz in the Venus spectra?](https://mysteriesdept.com/mysteries/venus-phosphine/questions/QST0CQY1TFR14XV/is-there-a-real-absorption-line-at-266-94-ghz-in-the-venus)·3 answers·0·0 following **Three answers, none ahead** None is ahead yet. See what would settle it. ## Where it stands Three answers have been proposed. None is ahead on the evidence yet. Three are still possible. Of the one narrower question under it, none is answered yet. ## Why it matters Sulphur dioxide has a transition close to 266.94 GHz and is abundant in the mesosphere; which molecule is responsible depends on line width, altitude and the strength of SO2's other lines⁠[[1]](https://mysteriesdept.com/sources/SRC0CQY1JNR4MPS/claimed-detection-of-ph3-in-the-clouds-of-venus-is)⁠[[2]](https://mysteriesdept.com/sources/SRC0CQY1K5C5E45/low-levels-of-sulphur-dioxide-contamination-of-venusian). ## Answers 3 [**None of these.** ](https://mysteriesdept.com/mysteries/venus-phosphine/answers/ANS0CQY212P4Z41/none-of-these) Not tested enough to call either way Evidence: none yet Still possible [**The absorption is mesospheric sulphur dioxide above 80 km.** ](https://mysteriesdept.com/mysteries/venus-phosphine/answers/ANS0CQY20B87QNB/the-absorption-is-mesospheric-sulphur-dioxide-above-80-km) Tested, but the results don't decide it Evidence: 1 for, 1 against Disputed [**The absorption is phosphine.** ](https://mysteriesdept.com/mysteries/venus-phosphine/answers/ANS0CQY1YWC27F9/the-absorption-is-phosphine) Tested, but the results don't decide it Evidence: 3 for, 2 against Disputed ## History 1. 2020[Greaves et al. puts forward: the absorption is phosphine.](https://mysteriesdept.com/sources/SRC0CQY1GQ84YF1/phosphine-gas-in-the-cloud-decks-of-venus) 1. 2020[Encrenaz et al.: iRTF/TEXES infrared spectra give a 3-sigma limit of 5 ppbv near the cloud tops.](https://mysteriesdept.com/sources/SRC0CQY1J645WRC/a-stringent-upper-limit-of-the-ph3-abundance-at-the-cloud)Against: The absorption is phosphine. 1. 2021[Lincowski et al. puts forward: the absorption is mesospheric sulphur dioxide above 80 km.](https://mysteriesdept.com/sources/SRC0CQY1JNR4MPS/claimed-detection-of-ph3-in-the-clouds-of-venus-is) 1. 2021[Greaves et al.: the line is wider than SO2 features and the SO2 abundance needed would be an extreme outlier.](https://mysteriesdept.com/sources/SRC0CQY1H6W1K9Y/reply-to-no-evidence-of-phosphine-in-the-atmosphere-of-venus)For: The absorption is phosphine. 1. 2021[Mogul et al.: pioneer Venus Large Probe mass spectra at 51.3 km are assigned in part to phosphine.](https://mysteriesdept.com/sources/SRC0CQY1KD652Z5/venus-mass-spectra-show-signs-of-disequilibria-in-the-middle)For: The absorption is phosphine. 1. 2021[Lincowski et al.: radiative transfer shows typical mesospheric SO2 fits the JCMT feature and the line forms above 80 km.](https://mysteriesdept.com/sources/SRC0CQY1JNR4MPS/claimed-detection-of-ph3-in-the-clouds-of-venus-is)For: The absorption is mesospheric sulphur dioxide above 80 km. 1. 2022[Cordiner et al.: sOFIA found no phosphine lines at 533 and 1,067 GHz, limit 0.8 ppb at 75–110 km.](https://mysteriesdept.com/sources/SRC0CQY1KN03DN2/phosphine-in-the-venusian-atmosphere-a-strict-upper-limit)Against: The absorption is phosphine. 1. 2022[Greaves et al.: sO2 contamination is estimated at about 10 per cent (JCMT) and 2 per cent or less (ALMA).](https://mysteriesdept.com/sources/SRC0CQY1K5C5E45/low-levels-of-sulphur-dioxide-contamination-of-venusian)For: The absorption is phosphine. 1. 2022[Greaves et al.: a JCMT SO2 spectrum within days of the 2017 data and simultaneous ALMA SO2 imply low contamination.](https://mysteriesdept.com/sources/SRC0CQY1K5C5E45/low-levels-of-sulphur-dioxide-contamination-of-venusian)Against: The absorption is mesospheric sulphur dioxide above 80 km. 1. 26 Oct 2026Asked on this site ## Discussion 0 [Add to the discussion](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TQJ1W8Q/if-the-line-is-real-is-it-phosphine-or-sulphur-dioxide%23discussion) Help with this question [ **Propose an answer** Something the evidence could support or rule out ] [ **Propose an answer** Something the evidence could support or rule out ](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TQJ1W8Q/if-the-line-is-real-is-it-phosphine-or-sulphur-dioxide%23add-answer) [ **Add evidence** A result for or against an answer ] [ **Add evidence** A result for or against an answer ](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TQJ1W8Q/if-the-line-is-real-is-it-phosphine-or-sulphur-dioxide%23add-evidence) [ **Ask a sub-question** A smaller question that would help settle this one ] [ **Ask a sub-question** A smaller question that would help settle this one ](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TQJ1W8Q/if-the-line-is-real-is-it-phosphine-or-sulphur-dioxide%23add-question) [ **Add a source** A paper, archive record or image ] [ **Add a source** A paper, archive record or image ](https://mysteriesdept.com/signin?next=/mysteries/venus-phosphine/questions/QST0CQY1TQJ1W8Q/if-the-line-is-real-is-it-phosphine-or-sulphur-dioxide%23add-source) Where it fits Phosphine in the clouds of Venus [**Is there a real absorption line at 266.94 GHz in the Venus spectra?** ](https://mysteriesdept.com/mysteries/venus-phosphine/questions/QST0CQY1TFR14XV/is-there-a-real-absorption-line-at-266-94-ghz-in-the-venus)Key question · 3 answers, inconclusive **If the line is real, is it phosphine or sulphur dioxide?** You're here · 3 answers, inconclusive [ Ask a question under this one ] Under this one [Can the claimed phosphine be reconciled with the upper limits from other instruments?](https://mysteriesdept.com/mysteries/venus-phosphine/questions/QST0CQY1TZC4EZE/can-the-claimed-phosphine-be-reconciled-with-the-upper)Most likely · the upper limits exclude phosphine at the claimed levels