If you were unlucky enough to face an angry Superman, this video would explain the incredible physics behind your annihilation. Superman physics is indeed more interesting than comic books.
If we assume Superman is bound by real life physics, then he cannot move his fist at the speed of light. Let’s assume his fist can only move at 99% the speed of light. At that speed, and if his fist has the average mass of 300g, the punch would have a total energy of 190 quadrillion joules, which is equivalent to 45 megatons of TNT. The energy released by Superman’s fist would be about 80 trillion Kelvin, which is five million times hotter than the core of our sun. Needless to say, your atoms would be disintegrated. The punch would leave a crater about one kilometer in diameter over 200 meters deep.