If we were to observe the light reflected from an extrasolar planet, the portion of the planet reflecting starlight toward us would change due to rotation and orbital motion. Reflected light will come from the planet's surface, but also from the clouds and atmosphere. It is possible that these two planetary components have different rotation speeds, and the presence of clouds might result in so much variability that complicates efforts to determine its rotational period. Here we show how the differential rotation of the atmosphere/clouds is detectable even on Earth for certain observing geometries.