The Sun produces approximately 35.7 octillion lumens (3.57 × 10^28 lumens) in total visible light output. This figure is derived by considering that the Sun emits about 93 lumens per watt of optical power, and given its total radiant power, this results in around 35.7 octillion lumens overall
. At the distance of Earth’s orbit (about 1 astronomical unit), the Sun delivers roughly 127,000 lumens per square meter of visible light. This means that each square meter facing the Sun at Earth's orbit receives an illuminance of about 127,000 lumens, which corresponds to very bright sunlight
. To put it into perspective, the total surface area of a sphere with a radius equal to the Earth-Sun distance is about 281.2 sextillion square meters. Multiplying this area by the lumens per square meter yields the total luminous output of the Sun in lumens, confirming the octillion-scale number
. In summary:
- Luminous efficacy of the Sun: ~93 lumens per watt
- Illuminance at Earth orbit: ~127,000 lumens/m²
- Total luminous output of the Sun: ~35.7 octillion lumens (3.57 × 10^28 lumens)
This immense brightness explains why direct sunlight is so intense and why it can be harmful to look at without protection
