1. Space Research Institute, Austrian Academy of Sciences, A-8042 Graz, Austria
2. Institut für Geophysik und Extraterrestrische Physik,
3. Institut für Theoretische Physik, TU Braunschweig, D-3300 Germany
4. Imperial College, London SW7 2BZ, UK
5. IGPP, University of California, Los Angeles, California 90095, USA
6. Swedish Institute of Space Physics, Kiruna, S-98128 Sweden
7. University of Sheffield, Sheffield S1 3JD, UK
8. Institute of Experimental Physics, Slovakia Academy of Sciences, Kosice, 04353 Slovakia
9. State Key Laboratory of Space Weather, Chinese Academy of Sciences, 100080 China
10. RSSD-ESTEC, Noordwijk 2000 AG, The Netherlands

Correspondence to: T. L. Zhang^1,9 Correspondence and requests for materials should be addressed to T.L.Z. (Email: tielong.zhang@oeaw.ac.at).

Abstract

Venus has no significant internal magnetic field¹, which allows the solar wind to interact directly with its atmosphere^2,3. A field is induced in this interaction, which partially shields the atmosphere, but we have no knowledge of how effective that shield is at solar minimum. (Our current knowledge of the solar wind interaction with Venus is derived from measurements at solar maximum^{3, 4, 5, 6}.) The bow shock is close to the planet, meaning that it is possible that some solar wind could be absorbed by the atmosphere and contribute to the evolution of the atmosphere^{7, 8}. Here we report magnetic field measurements from the Venus Express spacecraft³ in the plasma environment surrounding Venus. The bow shock under low solar activity conditions seems to be in the position that would be expected from a complete deflection by a magnetized ionosphere⁹. Therefore little solar wind enters the Venus ionosphere even at solar minimum.

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