Glowing Edward Cullen.

A lot of Twilight fans always wondered why does Edward Glow when he goes in the sunlight? Is that a special power or something more?

Stephenie never explained this mystery to fans, but some fans have their theories on that. One of the best is about bugs.
The vampires are compared with fleas that should fortify before full rehabilitation.
Like butterflies they can remember what happens to them when they were in other shape (human). So vampires are very similar to bugs and some of this insects has specific skin, so they can glow on the sunshine.
This theory is one of the best so far. If you have any theory about Edward glowing in the sunlight to share, you're welcome.