Figure 1 (image) New York University Share Print E-Mail Caption Helioseismology was used to measure the Sun's meridional flow (in miles per hour). This flow controls the evolution of the global magnetic field and the number of sunspots. Credit Courtesy of MPS (Z.-C. Liang). Usage Restrictions None Share Print E-Mail 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.