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South-polar features on Venus similar to those near the north pole

2007; Nature Portfolio; Volume: 450; Issue: 7170 Linguagem: Inglês

10.1038/nature06209

1476-4687

G. Piccioni, P. Drossart, A. Sánchez‐Lavega, R. Hueso, F. W. Taylor, Colin Wilson, D. Grassi, Ludmilla Zasova, M. L. Moriconi, A. Adriani, S. Lebonnois, A. Coradini, Bruno Bézard, F. Angrilli, G. Arnold, K. H. Baines, G. Bellucci, J. Benkhoff, J. P. Bibring, A. Blanco, M. I. Błęcka, R. W. Carlson, A. Di Lellis, T. Encrenaz, S. Érard, S. Fonti, V. Formisano, Thierry Fouchet, R. García, Rainer Haus, J. Helbert, N. Ignatiev, P. G. J. Irwin, Y. Langevin, M. Á. López‐Valverde, D. Luz, L. Marinangeli, V. Orofino, A. V. Rodin, M. Roos‐Serote, Bortolino Saggin, D. Stam, D. V. Titov, Guido Visconti, Massimo Zambelli, Eleonora Ammannito, Alessandra Barbis, R. Berlin, Carlo Bettanini, A. Boccaccini, Guillaume Bonnello, M. Bouyé, F. Capaccioni, Alejandro Cardesín‐Moinelo, Francesco Carraro, Giovanni Cherubini, M. Cosi, Michele Dami, Maurizio De Nino, Davide Del Vento, Marco Di Giampietro, Alessandro Donati, Olivier Dupuis, S. Espinasse, Anna Fabbri, Agnes Fave, Iacopo Ficai Veltroni, G. Filacchione, Katia Garceran, Yamina Ghomchi, Maurizio Giustini, Brigitte Gondet, Yann Hello, Florence Henry, Stefan Hofer, G. Huntzinger, J. Kachlicki, Ralph Knöll, Kouach Driss, Alessandro Mazzoni, Riccardo Melchiorri, Giuseppe Mondello, Francesco Monti, Christian Neumann, Fabrizio Nuccilli, Jérôme Parisot, Claudio Pasqui, Stefano Perferi, G. Peter, A. G. Piacentino, C. Pompei, Jean-Michel Réess, Jean‐Pierre Rivet, António Romano, N. Russ, Massimo Santoni, Adelmo Scarpelli, Alain Sémery, A. Soufflot, D. Stefanovitch, Enrico Suetta, Fabio Tarchi, Nazzareno Tonetti, F. Tosi, B. Ulmer,

Space Science and Extraterrestrial Life

ESA's Venus Express probe has been in orbit since April 2006. Eight research papers in this issue present new results from the mission, covering the atmosphere, polar features, interactions with the solar wind and the controversial matter of venusian lightning. Håkan Svedham et al. open the section with a review of the similarities and (mostly) differences between Venus and its 'twin', the Earth. Andrew Ingersoll considers the latest results, and also how the project teams plan to make the most of the probe's remaining six years of life. Venus has a bright 'dipole' double-eye feature at the centre of a vast vortex that rotates around the north pole, and is surrounded by a cold 'collar'. Observations of Venus' south polar region are reported, where clouds with morphology much like those around the north pole are seen, but rotating somewhat faster. Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright 'dipole' feature surrounded by a cold 'collar' at its north pole1,2,3,4. The polar dipole is a 'double-eye' feature at the centre of a vast vortex that rotates around the pole, and is possibly associated with rapid downwelling. The polar cold collar is a wide, shallow river of cold air that circulates around the polar vortex. One outstanding question has been whether the global circulation was symmetric, such that a dipole feature existed at the south pole. Here we report observations of Venus' south-polar region, where we have seen clouds with morphology much like those around the north pole, but rotating somewhat faster than the northern dipole. The vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper. The spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition.