The graphic on the cover shows the absolute Total Solar Irradiance (TSI) as measured by different exo-atmospheric radiometers. In 2005 the absolute TSI value measured by TIM was about 1361 W/m2, whereas the ACRIM III and VIRGO (DIARAD+PMO6V) absolute TSI values were about 1366 W/m2 during the same time. The paper called “Sources of Differences in On-Orbital Total Solar Irradiance Measurements and Description of a Proposed Laboratory Intercomparison” by J. J. Butler et al. (page 187 of this issue) provides a summary of the workshop and steps to understand the differences in the TSI values. The graphic was adapted from Greg Kopp’s presentation entitled “TIM Accuracy,” presented at TSI Uncertainty Workshop at NIST, July 2005. The cover was arranged by C. Carey.