SOLAR is an ESA science observatory on the Columbus Laboratory, which is part of the International Space Station. SOLAR was launched with Columbus on February 2008 aboard STS-122. It was externally mounted to Columbus with the European Technology Exposure Facility (EuTEF). SOLAR has three main space science instruments: SOVIM, SOLSPEC and SOL-ACES. Together they provide detailed measurements of the Sun’s spectral irradiance.