The sun will last, at its current brightness for 9 billion more years.
How long until the sun gets burned down to the point where it cannot sustain life on earth anymore?
I am more.
I want to know how much lux the sun emits on a bright day - i don't mean when one stares directly at the sun, but rather when one walks casually outside when the sun is shinning brightly.
The sun's energy comes primarily from fusion of light elements in its core.
It is estimated that a very small fraction of mass of the sun (~$10^{-12}$ times the abundance of hydrogen) is.