On the cover: False color image of our Milky Way galaxy from WMAP measurements. Red regions suggest thermal emission from dust. Blue is dominated by free-free emission. Green illustrates contributions from synchrotron and spinning dust emission. C. L. Bennett, et al., “Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Final Maps and Results,” The Astrophysical Journal Supplement Series 208 (2) (2013).