Zodiacal light

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 in spring, and just before sunrise in 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 in large part for the total skylight on a moonless night. Another phenomenon—a faint, but slightly increased, oval glow directly opposite the Sun—is called 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, most with mass around 150 micrograms.