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 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.
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.