A pyranometer is an instrument used to measure solar irradiance on a flat surface, typically used in meteorology and solar energy applications. However, there are several synonyms that can be used to describe this device. A solarimeter, or sunshine recorder, is a similar device that measures total solar radiation, while a radiometer measures the intensity of electromagnetic radiation. A lux meter, or light meter, measures the intensity of visible light. Additionally, a solarimeter, or pyrheliometer, is used to measure direct radiation from the sun. While these devices have different specific uses, they are all useful in measuring different aspects of solar energy.