Upper panel: measured total solar irradiance, binned in 1-day intervals, covering more than 40 yr of observations. The approximately 11-year solar cycle can be seen as the Sun’s brightness changes from almost constant during activity minima to highly variable during activity maxima. Lower panel: variability range of the TSI data, R_var, as a function of time. We define R_var as the difference between the 5th and 95th percentiles of the 1-day binned intensity in each 90-day period in time. The red curve shows a sine fit to the R_var time series with a period P_{cyc, var} = 10.98 ± 0.26 yr.