The Sun (IMAGE) Helmholtz-Zentrum Dresden-Rossendorf Caption Every 11 years the polarity of the sun's magnetic field is reversed. Could the weak tidal forces of Venus, the Earth and Jupiter directly influence the sun's activity? Credit NASA/SDO Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.