The variation in the Sun's output (TSI = Total Solar Irradiance) over the 11-year solar cycle is about 0.1%. This has been found by a number of spacecraft experiments beginning with ERB on Nimbus-7 launched in 1978. The transit of groups of active regions can show much larger variations of up to about 0.3%. Most, if not all, of this variation can be accounted for by magnetic activity, sunspots and faculae/network. Coefficients of multiple determination (R^2) are often of the order of 0.9. Using these results, we can display separately the effects of spots and faculae on the solar output. Several examples will be shown when there were large changes in the TSI. The question is, can these results be transferred in whole to understanding solar analogs. This research has been partially supported by grants from NASA and NSF.
