The Power of Kryptonite

If Superman comes into contact with Green Kryptonite, he instantly becomes very weak. With enough exposure, he could die. Kryptonite has this effect because of the way it interacts with Superman's cells.

Much of Superman's power comes from the Earth's yellow sun. His cells are like living photovoltaic, or solar, cells -- they can store the energy from sunlight. Inside a photovoltaic cell, light comes into contact with a semiconductor, like silicon. The light's energy releases electrons from the silicon, and an electric field forces them to flow in one direction. In this way, a solar cell produces electricity.

Photo courtesy Photo DOE/NREL Photo credit SunLine Transit Agency Superman? Is that you?

You could also compare Superman to a plant that uses photosynthesis to make its own food. Through photosynthesis, plants use energy from the sun to turn water and carbon dioxide into oxygen and sugar.

Plants use the sun to make food, and Superman uses the sun to make super powers.

It's unclear exactly which method best describes the way Superman's cells use sunlight, if either of them describe it at all. It's also unclear exactly why light from a yellow sun affects Superman in a way that light from a red sun does not. If Rao were a red dwarf, the explanation could be simple -- yellow stars are bigger, brighter and hotter than red dwarfs. However, Rao is a red giant, meaning it is bigger, brighter, and a little cooler than the Earth's sun. Although we do not know precisely why yellow light is so important, we do know that Superman needs it in order to have super powers.

There are a few possible explanations for how Green Kryptonite keeps Superman from getting power from the sun:

• The kryptonite radiation might displace the solar radiation responsible for Superman's powers.
• Kryptonite's ionizing radiation might displace electrons in Superman's cells, preventing the sort of electron movement found in solar cells.
• Kryptonite radiation may interrupt some other organic process within Superman's body.

As a result, Superman can no longer take advantage of the powers Earth's yellow sun gives him -- he loses his powers, and he may die.

The Power's Source The first Superman stories described Superman as a being from another planet and included no specific explanation for why he had super strength and other powers. Later stories explained that his abilities came from the difference in gravity between Earth and Krypton. Eventually, the explanation expanded to include the Earth's yellow sun.

The History of Kryptonite

Green Kryptonite is the most abundant and most frequently used form of kryptonite. But it wasn't always been part of the Superman universe, and it wasn't always green. An unpublished Superman story from the 1940s featured a precursor to kryptonite, a substance called K-metal. The deadly element itself made its debut in the "Superman" radio series -- not the comic book -- in 1943. Its original purpose was to give voice actor Bud Collyer, who played the role of Superman, a vacation. With Superman incapacitated by kryptonite, another voice actor could supply his incomprehensible moans, filling the role until Collyer returned.

Kryptonite made another radio appearance in 1945 and appeared in a movie serial in 1948. But it didn't find a place in the comics until "Superman" #61 in 1949, more than 10 years after Superman's debut in "Action Comics" #1. Radio scripts and comic book art portrayed the substance as red, grey, green and metallic, but eventually the writers settled on green as the color of kryptonite.

You'll Shoot Your Eye Out, Superman Even though the substance known as kryptonite wasn't part of the Superman world until 1943, the word "kryptonite" had its debut years earlier. Daisy -- maker of the Red Ryder air rifle -- produced a Superman tie-in called the Krypto-Raygun in 1940. According to the ads, it was made from "KRYPTONITE, the amazing metal from his birthplace." Read more about it at the Daisy Museum.

In addition to "plain" Green Kryptonite, multiple varieties have appeared on the scene through the years. These varieties are different isotopes of the same element, and they can come in different grades, or strengths. The different isotopes have distinctly different effects on Superman and other life forms, but these effects most likely all stem from the disruption of cells. Some varieties of kryptonite appeared in only one comic book issue or story arc. For example:

• Jewel Kryptonite, or Kryptonite 6, enhanced the powers of Kryptonians who had been sentenced to live in the Phantom Zone. It appeared in "Action Comics" #310.
• X-Kryptonite appeared in "Action Comics" #261. It caused a cat named Streaky to develop superpowers.
• Kryptonite Plus was an extra-potent variety that appeared in two story arcs.

In addition, red, white, blue and gold varieties of kryptonite, created through various means, appeared in the comic books until 1985. Click on the tabs below to see how each of these types were created and how they affected life forms.

By the 1970s, Kryptonite was everywhere -- common criminals had pieces stashed away as protection from Superman. In "Superman" #233, an experiment gone wrong transformed all of the Green Kryptonite on Earth into iron. "Superman" #255 eliminated it from the rest of the universe. But soon, the radioactive mineral was back.

The year 1985 marked a turning point for Superman, Kryptonite and the entire D.C. Comics universe, which had become a multiverse full of alternate worlds. A miniseries called "Crisis on Infinite Earths" made major changes to the comic books' reality. The miniseries is an example of retroactive continuity, or retcon. Retcon is an attempt to clean up years of comic book history and get rid of unnecessary characters, plot holes or, in this case, whole universes. These changes are retroactive -- the post-Crisis universe is not simply the way the D.C. Comics world works now; it's the way it has always worked.

In the post-Crisis reality, fewer versions of kryptonite exist, and the substance is relatively rare. Click the tabs below to see what kinds of kryptonite exist in the post-Crisis universe.

In addition to "Crisis on Infinite Earths," another recent retcon attempt is a miniseries called "Infinite Crisis," but it did not substantially affect the use or presence of kryptonite.

Check out the links on the next page to learn more about Superman, kryptonite, radioactivity and related topics.

A Super Mutt Although a lot of people remember Superman from comic books and movies, many of the things we associate with him come from the radio plays of the 1940s. Among them are: Kryptonite: The show couldn't go on without Bud Collyer, who provided the voice for Superman. But if Superman were exposed to kryptonite, he wouldn't need to speak. Another actor could fill in for a few days, providing the minimal voice Superman would need. Collyer was also the voice of Superman in animated shorts for TV and film. Catch phrases: Just about everything kids say when pretending to be Superman comes from audio drama, including, "Up, up and away," "This is a job for...Superman," "Look! Up in the sky! It's a bird! It's a plane! It's Superman," and "Faster than a speeding bullet, more powerful than a locomotive, able to leap tall buildings in a single bound." The original story of Kal-El's escape from Krypton also first appeared in 1940s newspaper comic strips rather than in comic books.