solar constant The rate at which solar energy, at all wavelengths, is received per unit area at the top level of Earth's atmosphere. The solar constant actually varies by about 0.3% over the 11-year solar cycle but averages about 1,368 W/m2. Each planet has its own planetary solar constant, ranging from Mercury (9936.9 W/m2) to Pluto (0.87 W/m2). Related category SOLAR TOPICS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) |