Sunrise Over Kilimanjaro . ... A group hiking at 6 am near the top of Mt. Kilimanjaro watched the rising sun peak above the clouds and the horizon light up red. ... The spectacular sunrise colors are caused by light scattering off the atmosphere and small cloud particles. ... A similar light scattering effect involving small airborne dust particles causes sunsets on Mars to be red and has been used to determine the sizes of particles in the rings of Saturn . ... NASA Official: Jay Norris. ...