It actually is white, so you are correct in assuming so. It only APPEARS to be a copper color because the Sun likes to play stupid Sun tricks on the eyes of humans by casting forth copper light upon the planet's surface. This reflection of false light then reaches our eyes and causes great distraught and confusion, all the while the Sun is swelling with pride and laughter, bearing witness to those simple humans who have fallen prey to his trickery. F*ck you, Sun.