Sometimes the sky itself seems to glow. Usually, this means you are seeing a cloud reflecting sunlight or moonlight. If the glow appears as a faint band of light running across the whole sky , you are probably seeing the combined light from the billions of stars that compose our Milky Way Galaxy . Such a glow is visible rising diagonally up to the right in the above image . If the glow is seen coming up from the horizon just before sunrise or just after sunset, however, you might be seeing something called zodiacal light . Pictured rising diagonally up to the left in the above image, zodiacal light is just sunlight reflected by tiny dust particles orbiting in our Solar System . Many of these particles were ejected by comets . The above image was taken just after sunset earlier this month from Ras Lanuf , Libya .
Best Astronomy Images: APOD Editor to speak in Philadelphia on Jan 5 and New York City on Jan 7