Because the molecules in the air scatter blue light all around, and it's from the sun, if you know pigments (blue yellow magenta green and red*) It gives off more blue that red light. thus, the aoura and vision of the sun is a mix of orange and red, because the blue light has been scattered, also, it's the colour reflecting back to your eyes.
What is love? (don't hurt me, baby don't hurt me, no more, no more*)
@Lance Shield Awww, I already answered that, hrmphrmphrmphrm,
Also, the answer to your question id the same answer as @Midnight Blaze 98.