Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Phosphine gas in the cloud decks of Venus

20 November 2020 Editor’s Note: The authors have informed the editors of Nature Astronomy about an error in the original processing of the ALMA Observatory data underlying the work in this Article, and that recalibration of the data has had an impact on the conclusions that can be drawn. Nature Astronomy is working with the authors to resolve the matter, but in the meantime, readers are cautioned against using the paper’s quantifications for the ALMA part of the dataset.

Matters Arising to this article was published on 16 July 2021

An Addendum to this article was published on 16 July 2021


Measurements of trace gases in planetary atmospheres help us explore chemical conditions different to those on Earth. Our nearest neighbour, Venus, has cloud decks that are temperate but hyperacidic. Here we report the apparent presence of phosphine (PH3) gas in Venus’s atmosphere, where any phosphorus should be in oxidized forms. Single-line millimetre-waveband spectral detections (quality up to ~15σ) from the JCMT and ALMA telescopes have no other plausible identification. Atmospheric PH3 at ~20 ppb abundance is inferred. The presence of PH3 is unexplained after exhaustive study of steady-state chemistry and photochemical pathways, with no currently known abiotic production routes in Venus’s atmosphere, clouds, surface and subsurface, or from lightning, volcanic or meteoritic delivery. PH3 could originate from unknown photochemistry or geochemistry, or, by analogy with biological production of PH3 on Earth, from the presence of life. Other PH3 spectral features should be sought, while in situ cloud and surface sampling could examine sources of this gas.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Spectra of PH3 1–0 in Venus’s atmosphere as observed with the JCMT.
Fig. 2: Spectra of Venus obtained with ALMA.
Fig. 3: JCMT and ALMA whole-planet spectra across the full passband common to both datasets.
Fig. 4: The process of estimating SO2 contamination of the PH3 line.
Fig. 5: Predicted maximum photochemical production of PH3 found to be insufficient to explain observations by more than four orders of magnitude.

Similar content being viewed by others

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request. The raw data are publicly available at (JCMT) and (ALMA). Source data are provided with this paper.

Code availability

Our reduction scripts that can be used with the raw data to reproduce the results shown are provided as Supplementary Software 1 (JCMT) and Supplementary Software 24 (ALMA).

Change history

  • 20 November 2020

    Editor’s Note: The authors have informed the editors of Nature Astronomy about an error in the original processing of the ALMA Observatory data underlying the work in this Article, and that recalibration of the data has had an impact on the conclusions that can be drawn. Nature Astronomy is working with the authors to resolve the matter, but in the meantime, readers are cautioned against using the paper’s quantifications for the ALMA part of the dataset.


  1. Baudino, J.-L. et al. Toward the analysis of JWST exoplanet spectra: identifying troublesome model parameters. Astrophys. J. 850, 150 (2017).

    Article  ADS  Google Scholar 

  2. Boston, P. J., Ivanov, M. V. & McKay, C. P. On the possibility of chemosynthetic ecosystems in subsurface habitats on Mars. Icarus 95, 300–308 (1992).

    Article  ADS  Google Scholar 

  3. McKay, C. P., Porco, C. C., Altheide, T., Davis, W. L. & Kral, T. A. The possible origin and persistence of life on Enceladus and detection of biomarkers in the plume. Astrobiology 8, 909–919 (2008).

    Article  ADS  Google Scholar 

  4. Pappalardo, R. T. et al. Does Europa have a subsurface ocean? Evaluation of the geological evidence. J. Geophys. Res. Planets 104, 24015–24055 (1999).

    Article  ADS  Google Scholar 

  5. Roth, L. et al. Transient water vapor at Europa’s south pole. Science 343, 171–174 (2014).

    Article  ADS  Google Scholar 

  6. Waite, J. H. et al. Cassini Ion and Neutral Mass Spectrometer: Enceladus plume composition and structure. Science 311, 1419–1422 (2006).

    Article  ADS  Google Scholar 

  7. Postberg, F. et al. Macromolecular organic compounds from the depths of Enceladus. Nature 558, 564–568 (2018).

    Article  ADS  Google Scholar 

  8. Oehler, D. Z. & Etiope, G. Methane seepage on Mars: where to look and why. Astrobiology 17, 1233–1264 (2017).

    Article  ADS  Google Scholar 

  9. Gillen, E., Rimmer, P. B. & Catling, D. C. Statistical analysis of Curiosity data shows no evidence for a strong seasonal cycle of Martian methane. Icarus 336, 113407 (2020).

    Article  Google Scholar 

  10. Sousa-Silva, C. et al. Phosphine as a biosignature gas in exoplanet atmospheres. Astrobiology 20, 235–268 (2020).

  11. Pasek, M. A., Sampson, J. M. & Atlas, Z. Redox chemistry in the phosphorus biogeochemical cycle. Proc. Natl. Acad. Sci. USA 111, 15468–15473 (2014).

    Article  ADS  Google Scholar 

  12. Bregman, J. D., Lester, D. F. & Rank, D. M. Observation of the ν 2 band of PH3 in the atmosphere of Saturn. Astrophys. J. 202, L55–L56 (1975).

    Article  ADS  Google Scholar 

  13. Tarrago, G. et al. Phosphine spectrum at 4–5 μm: analysis and line-by-line simulation of 2ν 2, ν 2 + ν 4, 2ν 4, ν 1, and ν 3 bands. J. Mol. Spectrosc. 154, 30–42 (1992).

    Article  ADS  Google Scholar 

  14. Noll, K. S. & Marley, M. S. in Planets Beyond the Solar System and the Next Generation of Space Missions (ed. Soderblom, D.) 155 (ASP, 1997).

  15. Visscher, C., Lodders, K. & Fegley, B. Atmospheric chemistry in giant planets, brown dwarfs, and low-mass dwarf stars. II. Sulfur and phosphorus. Astrophys. J. 648, 1181 (2006).

    Article  ADS  Google Scholar 

  16. Morowitz, H. & Sagan, C. Life in the clouds of venus? Nature 215, 1259 (1967).

    Article  ADS  Google Scholar 

  17. Limaye, S. S. et al. Venus’ spectral signatures and the potential for life in the clouds. Astrobiology 18, 1181–1198 (2018).

    Article  ADS  Google Scholar 

  18. Bains, W., Petkowski, J. J., Sousa-Silva, C. & Seager, S. New environmental model for thermodynamic ecology of biological phosphine production. Sci.Total Environ. 658, 521–536 (2019).

    Article  ADS  Google Scholar 

  19. Weisstein, E. W. & Serabyn, E. Detection of the 267 GHz J = 1-0 rotational transition of PH3 in Saturn with a new Fourier transform spectrometer. Icarus 109, 367–381 (1994).

    Article  ADS  Google Scholar 

  20. Cram, T. A directable modular approach to data processing. Astron. Astrophys. Suppl. Ser. 15, 339 (1974).

    ADS  Google Scholar 

  21. Warmels, R. et al. ALMA Cycle 6 Technical Handbook doc. 6.3 (ALMA, 2018).

  22. Encrenaz, T., Moreno, R., Moullet, A., Lellouch, E. & Fouchet, T. Submillimeter mapping of mesospheric minor species on Venus with ALMA. Planet. Space Sci. 113, 275–291 (2015).

    Article  ADS  Google Scholar 

  23. Jacquinet-Husson, N. et al. The 2015 edition of the GEISA spectroscopic database. J. Mol. Spectrosc. 327, 31–72 (2016).

    Article  ADS  Google Scholar 

  24. Gordon, I. E. et al. The HITRAN2016 molecular spectroscopic database. J. Quant. Spectrosc. Radiat. Transf. 203, 3–69 (2017).

    Article  ADS  Google Scholar 

  25. Tennyson, J. et al. The ExoMol database: molecular line lists for exoplanet and other hot atmospheres. J. Mol. Spectrosc. 327, 73–94 (2016).

    Article  ADS  Google Scholar 

  26. Kuczkowski, R. L., Suenram, R. D. & Lovas, F. J. Microwave spectrum, structure, and dipole moment of sulfuric acid. J. Am. Chem. Soc. 103, 2561–2566 (1981).

    Article  ADS  Google Scholar 

  27. Piccialli, A. et al. Mapping the thermal structure and minor species of Venus mesosphere with ALMA submillimeter observations. Astron. Astrophys. 606, A53 (2017).

    Google Scholar 

  28. Gurwell, M. A., Melnick, G. J., Tolls, V., Bergin, E. A. & Patten, B. M. SWAS observations of water vapor in the Venus mesosphere. Icarus 188, 288–304 (2007).

    Article  ADS  Google Scholar 

  29. Dartnell, L. R. et al. Constraints on a potential aerial biosphere on Venus: I. Cosmic rays. Icarus 257, 396–405 (2015).

    Article  ADS  Google Scholar 

  30. Sousa-Silva, C., Hesketh, N., Yurchenko, S. N., Hill, C. & Tennyson, J. High temperature partition functions and thermodynamic data for ammonia and phosphine. J. Quant. Spectrosc.Radiat. Transf. 142, 66–74 (2014).

    Article  ADS  Google Scholar 

  31. Sousa-Silva, C., Tennyson, J. & Yurchenko, S. N. Communication: tunnelling splitting in the phosphine molecule. J. Chem. Phys. 145, 091102 (2016).

  32. Krasnopolsky, V. A. Vega mission results and chemical composition of Venusian clouds. Icarus 80, 202–210 (1989).

    Article  ADS  Google Scholar 

  33. Lorenz, R. D. Lightning detection on Venus: a critical review. Prog. Earth Planet. Sci. 5, 34 (2018).

    Article  ADS  Google Scholar 

  34. Shalygin, E. V. et al. Active volcanism on Venus in the Ganiki Chasma rift zone. Geophys. Res. Lett. 42, 4762–4769 (2015).

    Article  ADS  Google Scholar 

  35. Grinspoon, D. H. & Bullock, M. A. in Exploring Venus as a Terrestrial Planet (eds Esposito, L. W., Stofan, E. R. & Cravens, T. E.) 191 (American Geophysical Union, 2007).

  36. Sánchez-Lavega, A., Lebonnois, S., Imamura, T., Read, P. & Luz, D. The atmospheric dynamics of Venus. Space Sci. Rev. 212, 1541–1616 (2017).

    Article  ADS  Google Scholar 

  37. Currie, M. J. et al. Starlink Software in 2013. Astron. Soc. Pac. Conf. Ser. 485, 391–394 (2014).

    ADS  Google Scholar 

  38. Currie, M. J. & Berry, D. S. KAPPA: Kernel Applications Package ascl:1403.022 (Astrophysics Source Code Library, 2014).

  39. Jenness., T. et al. Automated reduction of sub-millimetre single-dish heterodyne data from the James Clerk Maxwell Telescope using ORAC-DR. Mon. Not. R. Astron. Soc. 453, 73–88 (2015).

    Article  ADS  Google Scholar 

  40. Škoda, P., Draper, P. W., Neves, M. C., Andrešič, D. & Jenness, T. Spectroscopic analysis in the virtual observatory environment with SPLAT-VO. Astron. Comput. 7, 108–120 (2014).

    Article  ADS  Google Scholar 

  41. Sandor, B. J. & Clancy, R. T. First measurements of ClO in the Venus atmosphere–altitude dependence and temporal variation. Icarus 313, 15–24 (2018).

    Article  ADS  Google Scholar 

  42. Barnes, D. G., Briggs, F. H. & Calabretta, M. R. Postcorrelation ripple removal and radio frequency interference rejection for Parkes Telescope survey data. Radio Sci. 40, 1–10 (2005).

    Article  Google Scholar 

  43. Butler, B. ALMA Memo 594: Flux Density Models for Solar System Bodies in CASA (ALMA Memo Series, NRAO, 2012).

  44. Sandor, B. J. & Clancy, R. T. Water vapor variations in the Venus mesosphere from microwave spectra. Icarus 177, 129–143 (2005).

    Article  ADS  Google Scholar 

  45. Rimmer, P. B. & Helling, C. A chemical kinetics network for lightning and life in planetary atmospheres. Astrophys. J. Suppl. Ser. 224, 9 (2016).

    Article  ADS  Google Scholar 

  46. Krasnopolsky, V. A. Chemical kinetic model for the lower atmosphere of Venus. Icarus 191, 25–37 (2007).

    Article  ADS  Google Scholar 

  47. Rimmer, P. B. & Rugheimer, S. Hydrogen cyanide in nitrogen-rich atmospheres of rocky exoplanets. Icarus 329, 124–131 (2019).

    Article  ADS  Google Scholar 

  48. Krasnopolsky, V. A. S3 and S4 abundances and improved chemical kinetic model for the lower atmosphere of Venus. Icarus 225, 570–580 (2013).

    Article  ADS  Google Scholar 

  49. Zhang, X., Liang, M. C., Mills, F. P., Belyaev, D. A. & Yung, Y. L. Sulfur chemistry in the middle atmosphere of Venus. Icarus 217, 714–739 (2012).

    Article  ADS  Google Scholar 

  50. Burcat, A. & Ruscic, B. Third Millenium Ideal Gas and Condensed Phase Thermochemical Database for Combustion (with Update from Active Thermochemical Tables) (Argonne National Laboratory, 2005).

  51. Visscher, C. & Moses, J. I. Quenching of carbon monoxide and methane in the atmospheres of cool brown dwarfs and hot Jupiters. Astrophys. J. 738, 72 (2011).

    Article  ADS  Google Scholar 

  52. Lyons, J. R. An estimate of the equilibrium speciation of sulfur vapor over solid sulfur and implications for planetary atmospheres. J. Sulphur Chem. 29, 269–279 (2008).

    Article  Google Scholar 

  53. Kulmala, M. & Laaksonen, A. Binary nucleation of water–sulfuric acid system: comparison of classical theories with different H2SO4 saturation vapor pressures. J. Chem. Phys. 93, 696–701 (1990).

    Article  ADS  Google Scholar 

  54. Bierson, C. J. & Zhang, X. Chemical cycling in the Venusian atmosphere: a full photochemical model from the surface to 110 km. J. Geophys. Res. Planets (2019).

  55. Sander, R. Compilation of Henry’s law constants (version 4.0) for water as solvent. Atmos. Chem. Phys. 15, 4399–4981 (2015).

  56. Krasnopolsky, V. A. A photochemical model for the Venus atmosphere at 47–112 km. Icarus 218, 230–246 (2012).

    Article  ADS  Google Scholar 

  57. Seiff, A. et al. Models of the structure of the atmosphere of Venus from the surface to 100 kilometers altitude. Adv. Space Res. 5, 3–58 (1985).

    Article  ADS  Google Scholar 

  58. Keating, G. M. et al. Models of Venus neutral upper atmosphere: structure and composition. Adv. Space Res. 5, 117–171 (1985).

    Article  ADS  Google Scholar 

  59. Linstrom, P. J. & Mallard, W. G. The NIST Chemistry WebBook: a chemical data resource on the internet. J. Chem. Eng. Data 46, 1059–1063 (2001).

    Article  Google Scholar 

  60. Frost, B. R. in Oxide Minerals: Petrologic and Magnetic Significance (ed. Lindsley, D. H.) Ch. 1 (Mineralogical Society of America, 1991).

  61. Seager, S. et al. The Venusian lower atmosphere haze as a depot for desiccated microbial life: a proposed life cycle for persistence of the venusian aerial biosphere. Astrobiology (2020).

Download references


Venus was observed under JCMT Service Program S16BP007 and ALMA Director’s Discretionary Time programme 2018.A.00023.S. As JCMT users, we express our deep gratitude to the people of Hawaii for the use of a location on Mauna Kea, a sacred site. We thank M. Gurwell, I. Gordon and M. Knapp for useful discussions; personnel of the UK Starlink Project for training; S. Dougherty for award of ALMA Director’s discretionary time; and D. Petry and other Astronomers on Duty and project preparation scientists at ALMA for ensuring timely observations. The James Clerk Maxwell Telescope is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan; Academia Sinica Institute of Astronomy and Astrophysics; the Korea Astronomy and Space Science Institute; Center for Astronomical Mega-Science (as well as the National Key R&D Program of China with no. 2017YFA0402700). Additional funding support is provided by the Science and Technology Facilities Council of the United Kingdom and participating universities in the United Kingdom (including Cardiff, Imperial College and the Open University) and Canada. Starlink software is currently supported by the East Asian Observatory. ALMA is a partnership of ESO (representing its member states), NSF (United States) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. Funding for the authors was provided by STFC (grant ST/N000838/1, D.L.C.); Radionet/MARCUs through ESO (J.S.G.); the Japan Society for the Promotion of Science KAKENHI (grant no. 16H02231, H.S.); the Heising-Simons Foundation, the Change Happens Foundation, the Simons Foundation (495062, S.R.); the Simons Foundation (SCOL award 59963, P.B.R.). RadioNet has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 730562. J.S.G. is a Visitor at the Institute of Astronomy, University of Cambridge. S.R. is a SCOL Postdoctoral Fellow.

Author information

Authors and Affiliations



J.S.G. and A.M.S.R. analysed telescope data; H.S. developed a radiative transfer model; J.J.P. and W.B. worked out chemical kinetics and thermodynamics calculations; P.B.R., S.R., J.J.P., W.B. and S.S. worked on photochemistry; C.S.-S provided spectroscopic expertise and line parameter analysis; A.C., D.L.C., E.D.-M., H.J.F., C.S.-S., S.S., I.M.-W. and Z.Z. contributed expertise in astrochemistry, astrobiology, planetary science and coding; P.F., I.C., E.L. and J.H. designed, made and processed observations at the JCMT. J.S.G., A.M.S.R., W.B., J.J.P., D.L.C., S.S. and P.B.R. wrote the paper.

Corresponding author

Correspondence to Jane S. Greaves.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Astronomy thanks Kevin Zahnle and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Instrumental effects present in the JCMT data are illustrated.

Data are shown after an initial step of blanking 512 channels with increasing noise towards each end of the 8192 channel passband. Left: the 140 sub-observations are stacked vertically, with spectral channel on the X-axis and time on the Y-axis (earliest observation at the bottom). The black bars every 15th row denote gaps between observations. Signatures of reflected signals have here been fitted and subtracted, leaving the ripples with ~8,16 periods across 250 MHz. The spectra have been binned to 2.2 km/s velocity resolution for clarity; the Doppler-shifted Venus absorption is then centered around channel 62 of 112, counting from the left. Right: stages of the reduction for observation 1 (bottom 14 rows of data in the left panel; note that this example is for demonstration, and script Data S1 in fact reduces every row in the left panel separately). Top-right panel shows the 4th-order polynomial fit (red dotted curve) to the full passband of observation 1. Middle-right panel shows the subsequent residual, overlaid with a median-filter (red curve) and the 9th-order fit to this filtered data (black dashed curve). Bottom-right panel shows the next subsequent residual, with the data binned to 0.55 km/s resolution (a section around Venus’ velocity is highlighted with heavier bars). The overlaid red curve demonstrates the trend derived from the main Fourier components identified in the spectral ripple (via kappa task ‘fourier’).

Extended Data Fig. 2 Geometry of Venus is presented on the sky and by altitude.

Left panel: Illustration of the orientation of Venus as viewed at the time of our ALMA observation. The sub-Earth point (center) is at longitude 256o and latitude -0.6o. The Sun was overhead at longitude 194o and latitude +0.2o, hence longitudes beyond the terminator (> 284o) were in darkness. (For comparison, during JCMT observations, the planet was just over half illuminated, with the sub-solar point closer to the left limb.) Planetary rotation is from right to left. The color scale shows the continuum signal in our observations, illustrating that the polar caps appear cooler. The overlaid contours were only used for checking alignment of the longitude/latitude grid, and do not show real structures (contour spacings are of order the noise of ~0.1 Jy/beam; this is higher than the spectral channel noise due to dynamic range limitations with all baselines included). Magenta outlines were also temporary guides. The ellipse at lower-left indicates the size and orientation of the ALMA beam for the continuum data (the beam for the line data is very similar). Right panel: Illustration of the altitude-range above which the phosphine absorption can originate. The weighting function shows the altitudes where the continuum (thermal) emission arises, at 266 GHz (near the PH3 1-0 frequency but not affected by the absorption). The function peaks at 56 km and its FWHM spans approximately 53 to 61 km. The effect of uncertainties in the temperature profile of the Venusian atmosphere is to introduce systematics of order 2-3 km. The continuum emission has very high opacity, so our absorption observations do not trace altitudes below the peak of the weighting function.

Extended Data Fig. 3 Grid of PH3 1-0 spectra from ALMA is presented, illustrating the difficulties of detecting the phosphine line on scales of the restoring beam.

Each sub-plot spans 1.1 arcseconds on the planet (which has the same orientation as in Extended Data Fig. 2) and has an X-axis velocity range of ~ ±25 km/s. Blank boxes lie outside the planet (image mask has been applied).

Extended Data Fig. 4 Instrumental effects in the ALMA data are illustrated.

Left panel: PH3 spectra (offset vertically for clarity) illustrating the 12th-order polynomial functions selected empirically for fitting the spectral ripple seen with ALMA (leading to the results of Fig. 2). The planetary zones are polar (top), mid-latitude (centre) and equatorial (bottom) as defined in Table 1. The complexity of the ripple drove the choice of |v | = 5 km/s, i.e. line wings more than 5 km/s from the velocity of Venus were forced to zero. This value of |v| was chosen from test-region spectra where the line was clearly visible, and then applied to all the latitudinal bands. The polar spectrum is more noisy because it includes a smaller area (Extended Data Fig. 2) and because ripple effects are larger at the planetary limb. Right panel: spectra (red histograms) produced for the whole planet after applying the same reduction procedures to regions of the passband offset by 400 spectral channels either side of the expected line location. This produces narrow artefacts spanning only ~2 spectral channels, much less broad than the real line (blue histogram). The l:c values (integrated over ±5 km/s) of the artefacts are 18 ± 4 % of the value for the real line.

Extended Data Fig. 5 Deuterated water (HDO) is detected on Venus in the ALMA data.

A preliminary reduction of the whole-planet spectrum in the HDO 22,0-31,3 transition is shown. The overlaid red curve is from our radiative transfer model, calculated for 2.5 ppb abundance and processed with a 1st-order polynomial fit, as for the data. No correction has been made for line-dilution, so the abundance can be significantly under-estimated, depending on the scale over which the molecules are distributed.

Extended Data Fig. 6 The whole-planet PH3 1-0 spectrum (black histogram) from narrowband ALMA data is superposed on the equivalent data recorded simultaneously in the wideband spectral configuration (red dashed histogram).

The wideband spectrum has had a 1st-order polynomial subtracted to correct for mean level and overall slope. The narrowband spectrum (Fig. 2) is shown here at the 1.1 km/s resolution of the wideband data. The wideband absorption feature is substantially noisier due to a greater degree of spectral ripple (see e.g. the structure around -15 to -20 km/s), but it supports our PH3 detection, i.e. this detection cannot be attributed to an artefact of one correlator configuration.

Extended Data Fig. 7 Chemical pathways and energies are illustrated.

Upper panel: Reaction network used to predict maximum possible photochemical production rate for phosphine. Continuous lines are reactions for which kinetic data for the phosphorus species is known. Dotted lines are reactions for which kinetic data for the analogous nitrogen species is known, and was used here. Phosphorus species are shown in blue, reacting radicals in black. Lower panel: Heat map showing that phosphine production is not thermodynamically favored. The plot shows how many reaction/condition combinations there are with given Gibbs free energy as a function of altitude. Y-axis is height above the surface (altitude, in km); columns are bins of data in X, the Gibbs Free Energy (ΔG: -100 to +1240 kJ mol-1; 20 kJ mol-1 bins). Brighter-colored cells indicate more reactions for a given range of ΔG. There are no reactions occurring in the range where processes would be energetically favorable, i.e. there are no reactions/conditions where ΔG is negative and energy is released.

Extended Data Fig. 8 Inputs to the photochemical modelling are illustrated.

Top-left panel: Temperature-pressure profile used in photochemical modelling of the Venusian atmosphere, following refs. 46,56. Top-right panel: Eddy diffusion profile used here in photochemical modelling of the Venusian atmosphere, following refs. 46,56. Lower panel: Decomposition timescale for PH3 as a function of height, derived from the Lindemann approximation of the rate constant, employing a theoretical value of k (s-1) and an approximation of k0 (cm3 s-1) using kuni (s-1, blue), a simple unit-conversion estimate of k0 (orange), a scaled estimate of k0 based on ammonia decomposition (green), the timescale using only kuni (red), and the timescale at the high pressure limit (violet).

Extended Data Fig. 9 Context of the photochemical modelling is illustrated.

Top panel: Comparison of Venusian-atmosphere model to observations. Mixing ratios of various species are shown versus atmospheric height (km). Error bars span one order of magnitude, to help in comparing model predictions to observations. Bottom panel: Wind velocities that explain observed latitudinal variation, compared to observationally constrained zonal and meridional velocities. Velocities (m/s) are plotted versus atmospheric height (km). The blue shaded regions, bounded by blue lines, show the threshold velocities for the models in question. If the zonal wind velocity exceeds this threshold, then no longitudinal variation is expected, and if the meridional wind velocity exceeds this threshold, no latitudinal variation is expected. Estimated zonal63 (dashed line) and meridional64 (circles) wind velocities are also given.

Extended Data Fig. 10 An overview is presented of the potential pathways for phosphine production in the Venusian environment.

None of the known processes can be responsible for the amount of phosphine detected in the Venusian atmosphere.

Supplementary information

Supplementary Information

Supplementary discussion, Tables 1–3 and refs. 63–99.

Supplementary Software 1

The file is a sequence of commands in a linux shell script that process the JCMT spectra obtainable from the public archive. Reference name is

Supplementary Software 2

The file is a Python script used for initial calibration to produce the ALMA data cubes we analysed. Reference name is

Supplementary Software 3

The file is a Python script used for initial calibration to produce the ALMA data cubes we analysed. Reference name is

Supplementary Software 4

The file is a Python script used in imaging the ALMA data cubes. Reference name is

Source data

Source Data Fig. 1

Spectrum of Fig. 1b.

Source Data Fig. 2

Spectra of Fig. 2a,b.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Greaves, J.S., Richards, A.M.S., Bains, W. et al. Phosphine gas in the cloud decks of Venus. Nat Astron 5, 655–664 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing