The total → radiant energy, in all wavelengths,
emitted by the Sun in all directions. It is 3.828 × 1026 W or
3.828 × 1033 erg sec-1
(International Astronomical Union, Resolution B3, 14 August 2015,
Honolulu, USA). This is the luminosity unit conventionally
used to give the luminosities of stars. See also:
→ solar constant.
When the Earth first formed, 4.56 billion years ago, the Sun
radiated 30% less energy than it does today, thus giving rise to the so-called
→ faint early Sun paradox.
Ever since then,
its power has increased by 7% every billion years
(I. Ribas, 2009, arXiv:0911.4872).
See also: → solar; → luminosity.
