Recovered rotation periods from a Gaussian process fit to segments of each EIT version (2) light curve and the VIRGO light curve, split up by calendar year of observation. Each band has a small x-offset for plotting clarity. The gray shaded band shows the range of the true solar rotation period, from equator to pole, calculated analytically from the solar differential rotation equation given by Snodgrass & Ulrich (1990). The near-horizontal black curves represent the average behavior of migrating sunspot groups over the solar activity cycle, as calculated by Jiang et al. (2011). The true solar rotation period can be recovered from the 284 Å light curve in 26 out of 29 years, and from the VIRGO light curve in only 3 out of 29 years.