8.12  The Sun appears 400,000 times brighter than the full Moon in our sky.  How far from the Sun (in AU) would you have to go for the Sun to appear only as bright as the full Moon appears to us?  Compare your answer with the radius of Neptune's orbit.

Since brightness is related to the distance squared, we'd have to go the square root of 400,000 times 1 AU or 632 AU.  Neptune's orbit is 30 AU, so 21 times farther.  Although the Sun would appear as a point in the sky from Neptune, it would be a very bright one!