Lighting a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square metre (cd/m). The CGS unit of luminance is the stilb, which is equal to one candela per square centimetre or 10 kcd/m. The amount of useful light emitted from a source or the luminous flux is measured in lumen (lm). The SI unit of illuminance and luminous emittance, being the luminous power per area, is measured in Lux. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes
How to Measure a Planet? How to Measure a Planet? How to Measure a Planet? is fifth studio album by the Dutch alternative rock band The Gathering. It was released as a double CD on 9 November 1998 by Century Media Records. The album was recorded at Bauwhaus Studios, Amsterdam and Wisseloord Studios, Hilversum between July and October 1998 under the guidance of producer Attie Bauw. The theme of space travel runs through many of the songs on the album as well as on the cover and CD booklet. The track "Liberty Bell" was released as a single in Europe, as well as in Canada