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Can the claimed phosphine be reconciled with the upper limits from other instruments?

Asked 26 Oct 2026 by ·Part of If the line is real, is it phosphine or sulphur dioxide?·3 answers·0·0 following
Most likely: the upper limits exclude phosphine at the claimed levelsAhead on the evidence, not yet confirmed. It needs two reviews to be accepted.

Where it stands

Three answers have been proposed. The upper limits exclude phosphine at the claimed levels. leads, with evidence 1 for, 1 against: partly supported by its tests. Two are still possible.

Why it matters

Upper limits from SOFIA, IRTF and Venus Express sit at or below the claimed abundances⁠[1]⁠[2]⁠[3]. The detection survives only if phosphine varies strongly with altitude, time or place⁠[4].

Answers 3

Evidence: 1 for, 1 against
Most likely
None of these.
Not tested enough to call either way
Evidence: none yet
Still possible
Evidence: 2 for
Still possible

History

  1. Greaves et al. puts forward: phosphine varies with altitude and time, destroyed by sunlight high up and more abundant within the clouds,…
  2. Greaves et al.: independent measurements suggest under about 5 ppb above 60 km and up to about 100 ppb near 50 km.For: Phosphine varies with altitude and time, destroyed by sunlight high up and more abundant within the clouds,…
  3. Cordiner et al. puts forward: the upper limits exclude phosphine at the claimed levels.
  4. Cordiner et al.: sOFIA's 0.8 ppb limit is more stringent than earlier ground-based studies.For: The upper limits exclude phosphine at the claimed levels.
  5. Greaves et al.: the detection team disputes the SOFIA analysis.Against: The upper limits exclude phosphine at the claimed levels.
  6. Tang et al.: jCMT-Venus finds SO2 and H2O vary over years and with local solar time.For: Phosphine varies with altitude and time, destroyed by sunlight high up and more abundant within the clouds,…
  7. Asked on this site
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