Superman has always come with a twist. He is the Man of Steel with tremendous powers. Yet he has a main weakness.
The 1978 Superman movie shows this weakness when the villain Lex Luthor uses Kryptonite on Superman. The Man of Steel is instantly stunned and falls back, losing his strength. Once Luthor puts this Kryptonite on Superman’s neck, he is powerless.
Why does Kryptonite hurt Superman? We can turn to a scientific explanation to explain why Kryptonite harms Superman.
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Kryptonite and Superman
When Superman is on Earth, he is almost invincible. His powers soar due to the energy he gets from the Sun. However, Kryptonite withers away Superman’s strength.
Kryptonite originated with the radio show The Adventures of Superman from the 1940s. This space rock became Superman’s main weakness in the comics.
Kryptonite’s crippling power came from when Krypton, Superman’s home planet, exploded and created a radioactive compound called Kryptonite. The explosion produced “a glowing green rock or metal” that is hazardous to anyone from Krypton.
Greenish Kryptonite is the most common form of this compound. It was most likely brought to Earth with Superman’s arrival. Kryptonite came to Earth through a meteor shower that hit Smallville and usually is in a crystalline form.
Criminals like Lex Luthor sometimes get their hands on it to defeat Superman–in the Superman movie, Luthor stole it from an Ethiopian museum.
Hence, the green Kryptonite is Superman’s main weakness. But there are other forms of this compound.
For example, red Kryptonite is debilitating to Superman and causes wild shifts in moods. Gold Kryptonite is even more hazardous because it strips away Superman’s ability to use the Sun for his powers.
In comparison, green Kryptonite is only harmful when it is on or near Superman. Once its presence is removed, Superman’s powers quickly return.
How Has Kryptonite Been Used Against Superman?
Besides the Superman movie, Lex Luthor is one of the main villains who has used Kryptonite against Superman in the comics.
Luthor has deployed red Kryptonite and other synthetic varieties to stop Superman. As a scientist, albeit a greatly misguided one, Luthor has studied Kryptonite to thoroughly understand how it can undermine Superman. He even has a Kryptonite ring to keep Superman at bay.
We may expect this since Luthor has been the main antagonist to Superman since the comic’s creation. Yet, others have also used Kryptonite on Superman.
Metallo, for example, came with a Kryptonite heart. He releases radiation, or Slow Kryptonite, that can harm Superman.
In the 1980 DC Comics Presents No. 26, Green Lantern deploys green Kryptonite against Superman. In a 1960s comic, Superman’s friend Jimmy Olsen exposes the Man of Steel to Silver Kryptonite.
As a long-term enemy of Superman, General Dru-Zod has likewise tried to use Kryptonite to take out Superman and take over Earth. In Superman II, Kryptonite was used on Zod to defeat him at Superman’s Fortress of Solitude.
In these cases and others, Kryptonite is used as a tool to take away Superman’s powers. This compound has also been used metaphorically to represent humankind’s vulnerability to nuclear power.
Kryptonite is a danger to Superman and those he protects.
Why Does Kryptonite Hurt Superman?
The radioactive nature of Kryptonite explains why this compound is harmful to Superman. In essence, the radiation of this substance weakens Superman, causing nausea, pain, dizziness, and loss of consciousness.
Kryptonite interferes with Superman’s ability to absorb energy from the Sun in a way that corresponds with scientific understanding.
As radioactive elements give off radiation, they displace electrons and atoms in a human or Superman’s body and disrupt a cell’s ability to gather energy from the Sun–or in this case, have superpowers.
As with other types of radiation exposure like Uranium or Plutonium, Kryptonite radiation sickens and weakens those exposed to it. Kryptonite prevents the absorption of solar energy but it also displaces that “good” energy with “bad” radiation, resulting in the loss of superpowers.
Eventually, this radiation poisoning could lead to death.
Comic fans have also weighed in to clarify why Kryptonite hurts Superman. Since Kryptonite came from “the raw materials of Krypton,” its radiation is geared to harm those from the planet and disrupts Superman’s “bioelectric field.”
The cellular-to-bioelectric effects provide the main basis for why Kryptonite harms Superman so quickly.
Writing decisions also provide an explanation. Comic writers and screenwriters don’t have the time to show Kryptonite having a slow impact on Superman. They need to keep readers and audiences engaged.
What Else Can Hurt Superman?
Kryptonite is not the only substance that can harm Superman. Magic is another threat to the Man of Steel.
For example, Black Adam’s magic is a threat to Superman because it also undermines Superman’s powers. This magic infused in a thunderbolt can penetrate through Superman’s bioelectric field and make him weaker.
Another magic user, Doctor Fate, could use his power to defeat Superman. Doctor Fate’s magical skills could be enough to harm or defeat Superman.
The red sun Rao can also hurt Superman. This is the sun of Krypton and was not originally dangerous to those from this planet. However, as Superman spent more time on Earth and gained his powers from the Sun here, the red sun became dangerous.
The red sun’s radiation strips away Superman’s powers in a way that leaves Superman at a human level of powers. Yet, this radiation can also be used as a weapon and produces more devastating effects.
Superman is also vulnerable to mind control. Batman is one character who has used this hidden weapon on the Man of Steel and turned the latter into a destructive force.
Although Kryptonite is Superman’s main weakness, other vulnerabilities exist for Superman.
Superman and Kryptonite
Superman is the Man of Steel with tremendous powers. Yet, Kryptonite has continued to be his primary weakness.
Originating in radio to comic depictions of Superman, Kryptonite can take away Superman’s powers by exposing him to radiation. This radiation undermines Superman’s ability to generate his powers from the Sun.
As long as Superman continues, Kryptonite will pose a threat to him.
Todd Wahlstrom is a creative and analytical freelance writer and life-long Star Wars fan who has expanded into writing about the Marvel Cinematic Universe. He has written about recent shows such as The Mandalorian and Andor and classic topics like Darth Vader, the Jedi, and Boba Fett. His recent articles include the MCU’s Iron Man, Captain America, and Thor. Todd is the author of a non-fiction book, holds a Ph.D. in history, and enjoys hiking, running, and reading about science.