It has long been argued that Supergirl is actually more powerful than Superman, since she spent more time in space absorbing the rays of Earth’s yellow sun upon her trip to Earth. And while the validity of that stance remains to be seen, it is true that Supergirl has one invulnerability that makes Superman look like an absolute weakling.
Kara Zor-El or Kara Danvers aka Supergirl is Superman’s cousin who spent most of her early life on Krypton before the planet came to a cataclysmic end. Kara was sent to Earth in similar fashion as her baby cousin when she was a teenager, but while Kal-El’s trip was a straight-shot to Earth, Kara experienced unforeseen detours which caused her to arrive on Earth far later than Kal. When she arrived at her destination, Kal-El was already an adult and was well into his career as the world-renowned superhero, Superman. Following his lead, Kara took on the mantle of Supergirl and joined her cousin on his quest to protect the Earth from any threat it may face.
In Supergirl #25 by Kelley Puckett, Drew Johnson, and Lee Ferguson, Kara is running simulations of world-ending events to better prepare herself in the likelihood something like what she’s training for actually happens. As if due to tempting fate, Supergirl is later attacked by a villain named Reactron who launches an assault against her by shooting Supergirl with a powerful blast akin to a nuclear bomb. While she is knocked down, Supergirl is far from out of the fight and even seems as though she was barely phased by the explosion.
Supergirl’s reaction to basically being hit with a nuke proves how much tougher she is than Superman, at least in that regard. Superman has taken nuclear blasts to the face a number of times in the past to prevent them from decimating their intended targets with two examples being found in Superman/Wonder Woman #6 and The Dark Knight Returns. However, on both occasions, Superman was weakened immensely by the explosions as the energy they released seemed to drain the life force right out of him. Supergirl, on the other hand, just casually gets back up after taking the full-force of Reactron’s attack and keeps on fighting like it’s no big deal–not even approaching the emaciated reaction Superman has.
While Supergirl’s sheer strength could be the reason behind this disparity between Superman’s invulnerability and her own, it could also be due to the energy itself that Kara is blasted with in this issue. Reactron has access to far-off stars in the cosmos and can pull the energy from an entire sun from his body and use it as a devastating weapon. Since Kryptonians gain superpowers from the energy of specific suns, Reactron could have just hit her with another energy source, making the attack basically useless. However, it seems likely that Supergirl would have felt a surge in power rather than feeling the impacts of an attack if that was the case, and her immediate reaction was to think she was hit with a nuke upon their initial encounter. In other words, because of Supergirl’s ability to get blasted with an attack indistinguishable from a nuclear blast and get up like nothing happened, she proves that her invulnerability makes Superman look like a weakling.
