The rate at which energy reaches the earth's surface from the sun, usually taken to be 1,388 watts per square metre.
- ‘The heat shield will reach temperatures of up to 1800°C as it is exposed to energies 1000 times more intense than the solar constant.’
- ‘The solar constant is 1.37 kW m - 2, but the 24-hour average at the top of the atmosphere is of course much lower, and varies widely by geographic latitude and time of year.’
- ‘Solar sails can be used to adjust the earth's solar constant (in effect making it a variable that can be controlled).’
- ‘But the solar constant - the amount of sunlight received each second - is carefully monitored by spacecraft, and we know the sun's output is much too steady to be changing the temperature of Pluto.’
- ‘The solar constant isn't constant.’