the secret behind his invulnerability!
Not many people know this, but there are some stories that say Superman's invulnerability is not from inherent toughness of flesh, but from a superthin aura that surrounds him at all times. This is why the cape may get tattered in many battles, but no matter what the suit never comes off to leave a naked Kryptonian having on-panel battles with laser-toting aliens.
As everyone who has seen the trailers for Superman Returns knows, metal bullets bend on this aura, even when they're over the iris of the eye, but they are not repelled, so it's not electromagnetic.
http://time.com/4271903/science-of-superman-batman-v-superman/
By: Sherif Atta & Mohamed Taha