In most cases when you think about Superman, the first thing that comes to your mind isn’t his invulnerability, but his ability to fly. The two phrases, “up, up and away,” and “Look, up in the sky! It’s a bird! It’s a plane! It’s Superman!” are only related to the Man of Steel. We don’t associate any other hero with these iconic sayings even though there are countless others who can fly. But have you ever stopped and wondered how exactly is Superman able to defy gravity? Why is it that a Kryptonian can fly on Earth while others cannot?
Before we tell you the answers to this question, let’s give you a bit of history lesson. Just like Clark Kent first starts off with leaping tall buildings, and then gradually learns to stay suspended in the air & fly, the comics writers also evolved Superman as a character in the same way. Back when Superman was first created in 1938, he wasn’t given the ability to fly. He could only leap tall buildings. But in 1940s, the animators requested DC to grant Superman the ability to fly. That was when Sups was given permanent flight. As it turned out, that’s what distinguished him from other heroes (along with is other abilities).
Now coming to the scientific explanation as to how Superman and other Kryptonians can fly on Earth, but not on Krypton, the answer is hidden in the difference between Krypton and Earth’s physiology. The yellow sun of Earth is much more nurturing for the cells Kryptonians than the harsh red sun of Krypton. So, Earth’s sun makes Kryptonians stronger, and grants them all sorts of powers. But when we talk about flight, the answer is that Earth’s gravity is much weaker than Kryptons. It’s strong enough for humans but not Kryptonians. In fact, the gravitational force of Krypton was so strong that the inhabitants of the planet had to evolve by developing anti-gravity organs to move around like we do as normal humans on Earth.
So, with the kinder conditions on Earth and a gravitational force much weaker for Sups’ Kryptonian cells, his body is able to completely defy Earth’s gravity altogether. Obviously, it took some learning for Clark to control his flight. But his ability to fly is what makes him extremely special!
Source: Screen Rant