Zodiacal light is a faint, roughly triangular, diffuse white glow seen in the night sky that appears to extend up from the vicinity of the Sun along the ecliptic or zodiac. It is best seen just after sunset and before sunrise in spring and autumn when the zodiac is at a steep angle to the horizon. Caused by sunlight scattered by space dust in the zodiacal cloud, it is so faint that either moonlight or light pollution renders it invisible.
The zodiacal light decreases in intensity with distance from the Sun, but on very dark nights it has been observed in a band completely around the ecliptic. In fact, the zodiacal light covers the entire sky, being responsible for major part(60%) of the total skylight on a moonless night. There is also a very faint, but still slightly increased, oval glow directly opposite the Sun which is known as the gegenschein.
The dust forms a thick pancake-shaped cloud in the Solar System collectively known as the zodiacal cloud, which occupies the same plane as the ecliptic. The dust particles are between 10 and 300 micrometres in diameter, with most mass around 150 micrometres.
Read more about Zodiacal Light: Viewing, Origin, Appearance, History
Famous quotes containing the word light:
“True eloquence makes light of eloquence, true morality makes light of morality; that is to say, the morality of the judgment, which has no rules, makes light of the morality of the intellect.... To make light of philosophy is to be a true philosopher.”
—Blaise Pascal (1623–1662)