In late 2008, 12-month moving averages of sunspot number, number of spotless days, number of groups, area of sunspots, and area per group were reflective of sunspot cycle minimum conditions for cycle 24, these values being of or near record value. The first spotless day occurred in January 2004 and the first new-cycle, high-latitude spot was reported in January 2008, although old-cycle, low-latitude spots have continued to be seen through April 2009, yielding an overlap of old and new cycle spots of at least 16 mo. New-cycle spots first became dominant over old-cycle spots in September 2008. The minimum value of the weighted mean latitude of sunspots occurred in May 2007, measuring 6.6 deg, and the minimum value of the highest-latitude spot followed in June 2007, measuring 11.7 deg. A cycle length of at least 150 mo is inferred for cycle 23, making it the longest cycle of the modern era. Based on both the maximum-minimum and amplitude-period relationships, cycle 24 is expected to be only of average to below-average size, peaking probably in late 2012 to early 2013, unless it proves to be a statistical outlier. Wilson, Robert M. and Hathaway, David H. Marshall Space Flight Center SUNSPOTS; SUNSPOT CYCLE; ACTIVITY CYCLES (BIOLOGY); LATITUDE; TROPICAL REGIONS; MEAN; POLAR REGIONS

An interdisciplinary approach to solar physics, as eighty-nine contributors trace the evolution of the Sun and provide a review of our current understanding of both its structure and its role in the origin and evolution of the solar system.

This volume is dedicated to the Solar Dynamics Observatory (SDO), which was launched 11 February 2010. The articles focus on the spacecraft and its instruments: the Atmospheric Imaging Assembly (AIA), the Extreme Ultraviolet Variability Experiment (EVE), and the Helioseismic and Magnetic Imager (HMI). Articles within also describe calibration results and data processing pipelines that are critical to understanding the data and products, concluding with a description of the successful Education and Public Outreach activities. This book is geared towards anyone interested in using the unprecedented data from SDO, whether for fundamental heliophysics research, space weather modeling and forecasting, or educational purposes. Previously published in Solar Physics journal, Vol. 275/1-2, 2012. Selected articles in this book are published open access under a CC BY-NC 2.5 license at link.springer.com. For further details, please see the license information in the chapters.