... The ones included below are either of the sort that keeps coming up again and again, or else the answers make a special point, often going into details which might interest many users. ... Any time a rotating cloud of matter gets reduced in size--as it did when Earth originated--R gets smaller. ... We are about 200 solar radii from the Sun, and light weakens as the inverse of the distance squared, so 200 squared is 40,000, and the energy flow at the "surface" of the Sun is about 40,000 times larger....