Open up the Hypershade window, and pull out a remapHSV node. Hold Shift + the middle mouse button, and drag the specular file texture node onto the remapHSV and connect the file texture’s outColor to the Color channel of the remapHSV node via the Connection Editor. Connect the remapHsv node to the Specular Color of our ‘earthShader’ under its Specular Shading attributes.