Continuity mistake: In Kandor, Superman punches a hole in the ground and picks up a large chunk of the street out of the hole, but does not move from that spot. The shot changes to the robot's perspective of him about to throw the rock and shows his feet. The ground he just punched and picked up is in perfect condition at his feet. No hole, no cracks, no sign of the damage he just made. (00:41:15)
Chosen answer: If you'll notice, in order to change the trajectory of the missile, she blasts into it with her laser vision to make it vent and change its dynamics. This damage most likely is what caused the detonation by a chain reaction. Another possibility is that the missile was on a timer set to the amount of time it would take to reach the center of the sun. A missile designed to destroy a star in such a manner would obviously have an optimum effect from the very center. But the missile has to survive traveling through the star to get to the center, thus it would be made to withstand the plasma and heat to prevent impact or heat detonation. Thus it was likely timed.
Quantom X ★