Around sunset and sunrise the Martian sky is pinkish-red in color, but in the vicinity of the setting sun or rising sun it is blue. This is the exact opposite of the situation on Earth. However, during the day the sky is a yellow-brown "butterscotch" color. On Mars, Rayleigh scattering is usually a very small effect. It is believed that the color of the sky is caused by the presence of 1% by volume of magnetite in the dust particles. Twilight lasts a long time after the Sun has set and before it rises, because of all the dust in Mars's atmosphere. At times, the Martian sky takes on a violet color, due to scattering of light by very small water ice particles in clouds.