Was it ever explained how Superman got his X-ray/heat vision?

myrab51

The source of Superman's powers has changed subtly over the course of his history. It was originally stated that Superman's abilities derived from his Kryptonian heritage, which made him eons more evolved than humans.[56] This was soon amended, with the source for the powers now based upon the establishment of Krypton's gravity as having been stronger than that of the Earth. This situation mirrors that of Edgar Rice Burroughs' John Carter. As Superman's powers increased, the implication that all Kryptonians had possessed the same abilities became problematic for writers, making it doubtful that a race of such beings could have been wiped out by something as trifling as an exploding planet. In part to counter this, the Superman writers established that Kryptonians, whose native star Rao had been red, only possessed superpowers under the light of a yellow sun.[71] More recent stories have attempted to find a balance between the two explanations. http://en.wikipedia.org/wiki/Superman#Powers_and_abilities Sep 01 07, 9:01 AM