Everyone knows how super Superman is. Superman’s immense strength would allow him to punch a hole through any human, but he never does. Or Superman could use his strength to jump all the way up to the International Space Station, but again he never does. However, even though Superman’s strength is quite miraculous, the most famous superpower that Superman has is probably his most infamous as well—his Kryptonian heat vision, but how does it work?
Over the years Superman’s heat vision has been many things, from literally heat to lasers to pure energy, but what has been made clear is that he gets his abilities from the Sun. As well—in the comics—it has been established, at least once, that his heat vision is a release of the absorbed solar energy. But— as Superman’s energy release is dependent on the Sun—before we find out the power of his heat vision, we have to know two things. First, how much energy is the Sun emitting and second, how much energy can Superman absorb? The Sun is insanely powerful as each second it is emitting roughly 38*10^7 Exajoules of energy—or 3.8*10^26 joules. However, at the distance that the earth is from the Sun that means that every square meter of the earth is receiving around 1366 Joules per second—or 1366 Watts. But, what does all of this mean for Superman? Well, the average human body has around two square meters of skin and if we assume that all of Superman’s body surface area goes to absorbing sunlight—which includes UV, x-rays, etc.—then Superman at any one point in time would be receiving 2732 Watts.
Now that we’ve covered the boring science of Superman’s energy source, let’s get into real fun stuff— how long would Superman have to wait until he could bring down a building with his lasers and how powerful can Superman’s heat vision get? Before we being, let’s assume that Superman is a super-efficient solar panel that converts one hundred percent of solar energy into laser eye energy. With a few calculations, after one minute, Superman’s eyes could let out a burst of 168 Kilojoules—roughly the same amount of energy that one of the most powerful lasers in the world can put out at the National Ignition Facility. After an hour, Superman’s eyes could release 10 Megajoules of energy—10 times the kinetic energy of a vehicle traveling 160 km/h. After a whole day, Superman could release 240 Megajoules of energy—roughly the same amount of energy as exploding 57 Kilograms of TNT. After five days, Superman’s eyes could release 1 Gigajoule of energy—or like having a lightning bolt shoot from his eyes. And after one year, Superman could release the same amount of energy as the largest non-nuclear bomb ever designed—the Massive Ordnance Air Blast (MOAB). Now this is all amazing, but these blasts are just the tip of the iceberg for Superman’s abilities. About two years ago in Superman #38 the hero discovered that he could release all the solar energy in his cells at once resulting an explosion much like that of a nuclear bomb—and it was soon named “Super Flare”. As a result, he would instantly incinerate everything within a quarter-mile of him. But, how long would Superman have to wait to unleash his newest ability? If Superman wanted to go use this ability with the energy of a World War II nuclear weapon, or 63*10^12 Joules, then he would only have to save up for…713 years—which at that point he could just wait until everyone died.
However, there are ways to make Superman’s heat vision stronger or to shorten the amount of time Superman has to wait until he has the same amount of energy. Superman could either increase the surface area of his skin—which again sounds gross—or he could get closer to the Sun to receive more energy from it. If Superman flew to mercury then he would only have to wait…70 years to perform a WWII weapon sized Super Flare instead of 713 years.