A lighting system for lighting an interior space of a building, comprising: a diffuser; a solar tube, comprising an inlet configured to capture natural light from an exterior environment and an optical conduit configured to convey the natural light to the diffuser; and an artificial light source, wherein the artificial light source and the solar tube are disposed such that light emitted from the artificial light source mixes with the natural light supplied by the solar tube; a control unit characterized in that the artificial light source is configured to emit light with selectable intensity and color and/or color temperature; the lighting system further comprises a shutter configured to alter the intensity of the natural light admitted by the solar tube; wherein the lighting system further comprises: an all sky camera, configured to provide an image of the exterior environment within a field of view of said all sky camera; wherein said control unit is in communication with said artificial light source, said shutter and said all sky camera; wherein said control unit is configured to receive an environmental signal from said all sky camera and to extract spectral information from said image of the exterior environment, said spectral information comprising light intensity and color and/or color temperature from said image of the exterior environment and to output a first control signal to said artificial light source and a second control signal to said shutter, each in response to said environmental signal from said all sky camera; wherein said artificial light source is configured to output light of varying intensity and color and/or color temperature in response to said first control signal; and wherein said shutter is configured to adjust the intensity of natural light provided by the natural light illumination device in response to said second control signal. a diffuser; a solar tube, comprising an inlet configured to capture natural light from an exterior environment and an optical conduit configured to convey the natural light to the diffuser; and an artificial light source, wherein the artificial light source and the solar tube are disposed such that light emitted from the artificial light source mixes with the natural light supplied by the solar tube; a control unit characterized in that the artificial light source is configured to emit light with selectable intensity and color and/or color temperature; the lighting system further comprises a shutter configured to alter the intensity of the natural light admitted by the solar tube; wherein the lighting system further comprises: an all sky camera, configured to provide an image of the exterior environment within a field of view of said all sky camera; wherein said control unit is in communication with said artificial light source, said shutter and said all sky camera; wherein said control unit is configured to receive an environmental signal from said all sky camera and to extract spectral information from said image of the exterior environment, said spectral information comprising light intensity and color and/or color temperature from said image of the exterior environment and to output a first control signal to said artificial light source and a second control signal to said shutter, each in response to said environmental signal from said all sky camera; wherein said artificial light source is configured to output light of varying intensity and color and/or color temperature in response to said first control signal; and wherein said shutter is configured to adjust the intensity of natural light provided by the natural light illumination device in response to said second control signal. an all sky camera, configured to provide an image of the exterior environment within a field of view of said all sky camera; wherein said control unit is in communication with said artificial light source, said shutter and said all sky camera; wherein said control unit is configured to receive an environmental signal from said all sky camera and to extract spectral information from said image of the exterior environment, said spectral information comprising light intensity and color and/or color temperature from said image of the exterior environment and to output a first control signal to said artificial light source and a second control signal to said shutter, each in response to said environmental signal from said all sky camera; wherein said artificial light source is configured to output light of varying intensity and color and/or color temperature in response to said first control signal; and wherein said shutter is configured to adjust the intensity of natural light provided by the natural light illumination device in response to said second control signal.