Phosphine on Venus: aliens or not?

UnprovenNot explained, but no evidence it is alien either. Usually too little data.

The claim

"A gas made by microbes on Earth was found in Venus's clouds."

A team led by Jane Greaves reported phosphine in Nature Astronomy, using the JCMT and ALMA telescopes.

On Earth phosphine is made mainly by microbes and industry, which is why the detection made headlines.
Reanalyses found problems with the data processing; the ALMA signal shrank after a calibration error was fixed.
Some argued the signal was sulphur dioxide; others suggested volcanic or unknown chemical sources.
Follow-up observations have given mixed results.

A Venus probe sampling the clouds directly (such as the planned DAVINCI mission) would settle it. Weigh the explanations and vote.

Unproven Disputed detection, with possible non-living sources.

Checked 31 October 2026. Spotted a newer source? Tell us.

Our summary of the main hypotheses, with what supports and what counts against each one.

A data processing error
For The ALMA signal shrank after a calibration error was fixed, and reanalyses found problems.
Against The original team says some signal remains in both telescopes.
Sulphur dioxide, not phosphine
For SO2 has a line very close to phosphine's, and Venus is full of it.
Against The original team disputes the line identification.
Real phosphine from volcanoes or unknown chemistry
For Venus's chemistry is poorly known; volcanoes could release phosphorus.
Against Models struggle to make enough phosphine without life.
Microbes in the cloud layer
For The clouds at 50 to 60 km have Earth-like temperatures and pressures.
Against They are also extremely acidic and dry; the signal itself is disputed.

One vote per visitor. Results appear after you vote.

NASA's DAVINCI probe, planned to drop through Venus's atmosphere around the early 2030s.
Rocket Lab's small private Venus probe, which has slipped several times.