How can superman fly?

In space superman flies because the gravitons can produce gravitational force and superman can use this force to propel himself across various planets. Since gravitational force of two bodies of mass is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. read more

The source of Superman's powers has changed subtly over the course of his history. It was originally stated that Superman's abilities derived from his Kryptonian heritage, which made him eons more evolved than humans. read more